Modified ionomer composition

ABSTRACT

The present invention relates to golf balls and golf ball components comprising a blend of one or more ionomers mixed with one or more metal or ammonium salts of chelating agent. The resulting modified ionomer compositions have improved proccessability as shown by the increase in melt flow index ( 12 ) as compared to the unmodified ionomer analogs while demonstrating an increase in resiliency or speed as shown by increasing COR, while maintaining or showing only a slight increase in hardness as measured by Shore D.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/645,345, filed Dec. 22, 2009, which claims the benefit of U.S.Provisional Application No. 61/140,510 filed Dec. 23, 2008 and U.S.Provisional Application No. 61/140,513 filed Dec. 23, 2008, each ofwhich are incorporated herein by reference in their entirety.

BACKGROUND

The present invention relates to a composition suitable for sportsequipment in general, and more particularly to a composition suitablefor use in golf ball manufacture. In one embodiment, the novelcomposition of the present invention is used in the manufacture of agolf ball comprising a core, a cover layer and, optionally, one or moreinner cover layers. In one preferred embodiment, a golf ball isdisclosed in which the cover layer comprises the novel composition ofthe present invention. In another preferred embodiment, a golf ball isdisclosed in which at least one intermediate layer comprises the novelcomposition of the present invention.

Description of Related Art

The application of synthetic polymer chemistry to the field of sportsequipment has revolutionized the performance of athletes in many sports.One sport in which this is particularly true is golf, especially asrelates to advances in golf ball performance and ease of manufacture.For instance, the earliest golf balls consisted of a leather coverfilled with wet feathers. These “feathery” golf balls were subsequentlyreplaced with a single piece golf ball made from “gutta percha,” anaturally occurring rubber-like material. In the early 1900's, the woundrubber ball was introduced, consisting of a solid rubber core aroundwhich rubber thread was tightly wound with a gutta percha cover.

More modern golf balls can be classified as one-piece, two-piece,three-piece or multi-layered golf balls. One-piece balls are molded froma homogeneous mass of material with a dimple pattern molded thereon.One-piece balls are inexpensive and very durable, but do not providegreat distance because of relatively high spin and low velocity.Two-piece balls are made by molding a cover around a solid rubber core.These are the most popular types of balls in use today. In attempts tofurther modify the ball performance especially in terms of the distancesuch balls travel and the feel transmitted to the golfer through theclub on striking the ball, the basic two piece ball construction hasbeen further modified by the introduction of additional layers betweenthe core and outer cover layer. If one additional layer is introducedbetween the core and outer cover layer a so called “three-piece ball”results and similarly, if two additional layers are introduced betweenthe core and outer cover layer, a so called “four-piece ball” results,and so on.

Golf ball covers were previously made from balata rubber which wasfavored by some players because the softness of the cover allows them toachieve spin rates sufficient to allow more precisely control of balldirection and distance, particularly on shorter approach shots. Howeverbalata-covered balls, although exhibiting high spin and soft feel, wereoften deficient in terms of the velocity of the ball when it leaves theclub face which in turn affects the distance the ball travels.

This distance is directly related to the coefficient of restitution(“C.O.R.”) of the ball. The coefficient of restitution of a one-piecegolf ball is a function of the ball's composition. In a two-piece or amulti-layered golf ball, the coefficient of restitution is a function ofthe properties of the core, the cover and any additional layer. Whilethere are no United States Golf Association (“USGA”) limitations on thecoefficient of restitution values of a golf ball, the USGA requires thatthe golf ball cannot exceed an initial velocity of 255 feet/second. As aresult, golf ball manufacturers generally seek to maximize thecoefficient of restitution of a ball without violating the velocitylimitation.

Accordingly, a variety of golf ball constructions have been developed inan attempt to provide spin rates and a feel approaching those of balatacovered balls, while also providing a golf ball with a higher durabilityand overall distance. This has resulted in the emergence of balls, whichhave a solid rubber core, a cover, and one, or more so calledintermediate layers, as well as the application of new materials to eachof these components.

A material which has been often utilized in more modern golf balls isthe family of ionomer resins developed in the mid-1960's, by E.I. DuPontde Nemours and Co., and sold under the trademark SURLYN®. These ionomerresins have, to a large extent, replaced balata as a golf ball coverstock material. Preparation of such ionomers is well known, for examplesee U.S. Pat. No. 3,264,272 (the entire contents of which are hereinincorporated by reference). Generally speaking, commercial ionomersconsist of a polymer of a mono-olefin, e.g., an alkene, with anunsaturated mono- or dicarboxylic acids having 3 to 12 carbon atoms. Anadditional monomer in the form of a mono- or dicarboxylic acid ester mayalso be incorporated in the formulation as a so-called “softeningcomonomer.” The acid groups in the polymer are then neutralized tovarying degrees by addition of a neutralizing agent in the form of abasic metal salt.

Today, there are a wide variety of commercially available ionomer resinsbased both on copolymers of ethylene and (meth)acrylic acid orterpolymers of ethylene and (meth)acrylic acid and (meth)acrylate, allof which many of which are be used as a golf ball component. Theproperties of these ionomer resins can vary widely due to variations inacid content, softening comonomer content, the degree of neutralization,and the type of metal ion used in the neutralization.

More recent developments in the field have attempted to utilize thevarious types of ionomers, both singly and in blend compositions tooptimize the often conflicting golf ball performance requirements ofhigh C.O.R. and ball velocity, and cover durability, with the need for aball to spin and have a so-called soft feel on shorter iron shots.However, the incorporation of more acid in the ionomer and/or increasingits degree of neutralization results in a material with increasedpolarity, and hence one which is often less compatible with otherpotential blend materials. Also increasing the acid content of theionomer while increasing C.O.R. may render the ball too hard and brittlecausing a loss of shot feel, control (i.e., the ability to spin theball) and may render the cover too brittle and prone to prematurefailure. Finally, the incorporation of more acid in the ionomer and/orincreasing its degree of neutralization typically results in an increasein melt viscosity which in turn greatly decreases the processability ofthese resins. Attempts to mediate these effects by adding softerterpolymeric ionomers to high acid ionomer compositions to adjust thehardness and improve the shot “feel” often result in concomitant loss ofC.O.R. and hence distance.

In addition, various hard-soft ionomer blends, that is, mixtures ofionomer resins, which are significantly different in hardness and/orflexural modulus, have been evaluated for use in golf balls. Forinstance, U.S. Pat. No. 4,884,814 discloses the blending of various hardmethacrylic based ionomer resins with similar or larger quantities ofone or more “soft” ionomer methacrylic acid based ionomer resins (i.e.,those ionomer resins having a hardness from about 25 to 40 as measuredon the Shore D scale) to produce relatively low modulus golf ball covercompositions that are not only softer than the prior art hard ionomercovers but also exhibit a sufficient degree of durability for repetitiveplay. These relatively low modulus cover compositions were generallycomprised of from about 25 to 70% of hard ionomer resins and from about30 to 75% of soft ionomer resins.

Also, U.S. Pat. No. 5,324,783 discloses golf ball cover compositionscomprising a blend of a relatively large amount, e.g., 70-90 wt. %, ofhard ionomer resins with a relatively low amount, e.g., 10 to about25-30 wt. %, of soft ionomers. The hard ionomers are sodium or zincsalts of a copolymer of an olefin having from 2 to 8 carbon atoms and anunsaturated monocarboxylic acid having from 3 to 8 carbon atoms. Thesoft ionomer is a sodium or a zinc salt of a terpolymer of an olefinhaving from 2 to 8 carbon atoms, methacrylic acid and an unsaturatedmonomer of the acrylate ester class having from 1 to 21 carbon atoms.

In order to further extend the range of properties of the ionomer resinsto optimize golf ball performance, additional components have been addedto them as “modifiers.” For example, U.S. Pat. No. 4,104,216 (Clampitt)discloses ionomers modified with 5-50 weight percent of a long chain(un)saturated fatty acid.

Also, Japanese Patent Application No. 48/70757 discloses ionomersmodified with a high level of a low molecular weight saturated orunsaturated carboxylic acid or salt or anhydride, specifically 10 to 500parts per 100 parts by weight of ionomer. The carboxylic acid may have 1to 100 hydrocarbon carbon chain units. Stearic, citric, oleic andglutamic acid and/or salts are exemplified.

U.S. Pat. Nos. 5,312,857 and 5,306,760 disclose cover compositions forgolf ball construction comprising mixtures of ionomer resins and 25-100parts by weight of various fatty acid salts (i.e., metal stearates,metal oleates, metal palmitates, metal pelargonates, metal laurates,etc.).

U.S. Pat. No. 6,100,321 and U.S. Patent Publication No. 2003/0158312 A1,disclose ionomer compositions, which are modified with 25 to 100 partsby weight of a fatty acid salt such as a metal stearate, for theproduction of golf balls with good resilience and high softness. Unlikethe earlier mentioned patents, which have employed metal stearates as afiller material, these patents disclose the use of relatively low levelsof a stearic acid moiety, especially calcium stearate, to modifyionomers to produce improved resilience for a given level of hardness orPGA Compression values. The stearate-modified ionomers are taught asbeing especially useful when the ionomer is formulated for use as a golfball core, center, one-piece ball, or as a soft golf ball cover.

Subsequent patent applications have furthered the use of such modifiedionomers in golf ball covers. For example U.S. Pat. No. 6,329,458 isdirected to a golf ball cover comprising an ionomer resin and a metal“soap,” e.g., calcium stearate. Finally, U.S. Pat. No. 6,616,552discloses a golf ball including a multi-layer cover, one layer of whichincludes a heated mixture of an ionomer resin and a metal salt of afatty acid, e.g., calcium stearate.

However, there remains a need for new materials with equivalent orimproved properties to the ionomer resins of the prior art for use ingolf ball manufacture, but which but which are not plasticized in thesense of reduced modulus and stiffness. There also remains a need fornew materials, which are more compatible with other resins, and whichalso do not give a hard feel to the golf ball or render it brittle andprone to failure and which do not require addition of softerterpolymeric ionomers which can cause a loss of C.O.R. It would also behighly advantageous if such new materials would exhibit increased C.O.R.and modulus, and still be easily processable by having a low meltviscosity, as evinced by a high melt flow index.

The present invention relates to golf balls and golf ball componentscomprising a blend of one or more ionomers mixed with one or more metalor ammonium salts of a chelating agent. Illustrative chelating agentsinclude metal and/or ammonium salts of unsaturated polycarboxylic acidsas well as chelating agents including metal and/or ammonium salts havingboth amine and carboxylic acid functionality. In the case of a chelatingagent comprising one or metal or ammonium salts of an unsaturatedpolycarboxylic acid, such polymers are distinct from the polymersdescribed as ionomers in the present application.

The resulting modified ionomer compositions have improved processabilityas shown by the increase in melt flow index (I2) as compared to theunmodified ionomer analogs while demonstrating an increase in resiliencyor speed as shown by increasing COR, while maintaining or showing only aslight increase in hardness as measured by Shore D.

SUMMARY

In one embodiment a golf ball is disclosed which includes (i) a corecomprising a center, (ii) an outer cover layer; and (iii) one or moreintermediate layers, where at least one of the outer cover layer orintermediate layer includes a blend composition of A) from about 75 toabout 99 wt % (based on the combined weight of Components A and B) ofone or more ionomers; and B) from about 1 to about 25 wt % (based on thecombined weight of Components A and B) of one or more chelating agentsalts; the blend composition having a flexural modulus from about 5 toabout 500 kpsi, and a Shore D hardness from about 25 to about 85.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates a three-piece golf ball 1 comprising a solid centeror core 2, an intermediate layer 3, and an outer cover layer 4.

FIG. 2 illustrates a 4-piece golf ball 1 comprising a core 2, and anouter cover layer 5. an inner intermediate layer 3, and an outerintermediate layer 4.

Although FIGS. 1 and 2 illustrate only three- and four-piece golf ballconstructions, golf balls of the present invention may comprise from 1to at least 5 intermediate layer(s), preferably from 1 to 3 intermediatelayer(s), more preferably from 1 to 2 intermediate layer(s).

DETAILED DESCRIPTION

Any numerical values recited herein include all values from the lowervalue to the upper value in increments of one unit provided that thereis a separation of at least 2 units between any lower value and anyhigher value. As an example, if it is stated that the amount of acomponent or a value of a process variable is from 1 to 90, preferablyfrom 20 to 80, more preferably from 30 to 70, it is intended that valuessuch as 15 to 85, 22 to 68, 43 to 51, 30 to 32 etc. are expresslyenumerated in this specification. For values, which have less than oneunit difference, one unit is considered to be 0.1, 0.01, 0.001, or0.0001 as appropriate. Thus all possible combinations of numericalvalues between the lowest value and the highest value enumerated hereinare said to be expressly stated in this application.

The term “(meth)acrylic acid copolymers” is intended to mean copolymersof methacrylic acid and/or acrylic acid.

The term “(meth)acrylate” is intended to mean an ester of methacrylicacid and/or acrylic acid.

The term “partially neutralized” is intended to mean an ionomer with adegree of neutralization of less than 100 percent.

The term “hydrocarbyl” is intended to mean any aliphatic,cycloaliphatic, aromatic, aryl substituted aliphatic, aryl substitutedcycloaliphatic, aliphatic substituted aromatic, or cycloaliphaticsubstituted aromatic groups. The aliphatic or cycloaliphatic groups arepreferably saturated. Likewise, the term “hydrocarbyloxy” means ahydrocarbyl group having an oxygen linkage between it and the carbonatom to which it is attached.

As used herein, the term “core” is intended to mean the elastic centerof a golf ball. The core may have one or more “core layers” of elasticmaterial, which are usually made of rubbery material such as dienerubbers.

The term “cover layer” is intended to mean the outermost layer of thegolf ball; this is the layer that is directly in contact with paintand/or ink on the surface of the golf ball. If the cover consists of twoor more layers, only the outermost layer is designated the cover layer,and the remaining layers (excluding the outermost layer) are commonlydesignated intermediate layers as herein defined. The term “outer coverlayer” as used herein is used interchangeably with the term “coverlayer.”

The term “intermediate layer” may be used interchangeably herein withthe terms “mantle layer” or “inner cover layer” and is intended to meanany layer(s) in a golf ball disposed between the core and the outercover layer. Should a ball have more than one intermediate layer, thesemay be distinguished as “inner intermediate” or “inner mantle” layerswhich are used interchangeably to refer to the intermediate layer nearerthe core and further from the outer cover, as opposed to the “outerintermediate” or “outer mantle layer” which are also usedinterchangeably to refer to the intermediate layer further from the coreand closer to the outer cover.

The term “prepolymer” as used herein is intended to mean any materialthat can be further processed to form a final polymer material of amanufactured golf ball, such as, by way of example and not limitation, apolymerized or partially polymerized material that can undergoadditional processing, such as crosslinking.

A “thermoplastic” as used herein is intended to mean a material that iscapable of softening or melting when heated and of hardening again whencooled. Thermoplastic polymer chains often are not cross-linked or arelightly cross-linked using a chain extender, but the term“thermoplastic” as used herein may refer to materials that initially actas thermoplastics, such as during an initial extrusion process orinjection molding process, but which also may be cross-linked, such asduring a compression molding step to form a final structure.

A “thermoset” as used herein is intended to mean a material thatcross-links or cures via interaction with as crosslinking or curingagent. Crosslinking may be induced by energy, such as heat (generallyabove 200° C.), through a chemical reaction (by reaction with a curingagent), or by irradiation. The resulting composition remains rigid whenset, and does not soften with heating. Thermosets have this propertybecause the long-chain polymer molecules cross-link with each other togive a rigid structure. A thermoset material cannot be melted andre-molded after it is cured. Thus thermosets do not lend themselves torecycling unlike thermoplastics, which can be melted and re-molded.

The term “thermoplastic polyurethane” as used herein is intended to meana material prepared by reaction of a prepared by reaction of adiisocyanate with a polyol, and optionally addition of a chain extender.

The term “thermoplastic polyurea” as used herein is intended to mean amaterial prepared by reaction of a prepared by reaction of adiisocyanate with a polyamine, with optionally addition of a chainextender.

The term “thermoset polyurethane” as used herein is intended to mean amaterial prepared by reaction of a diisocyanate with a polyol, and acuring agent.

The term “thermoset polyurea” as used herein is intended to mean amaterial prepared by reaction of a diisocyanate with a polyamine, and acuring agent.

A “urethane prepolymer” as used herein is intended to mean the reactionproduct of diisocyanate and a polyol.

A “urea prepolymer” as used herein is intended to mean the reactionproduct of a diisocyanate and a polyamine.

The term “zwitterion” as used herein is intended to mean a form of thecompound having both an amine group and carboxylic acid group, Component(B), where both are charged and where the net charge on the compound isneutral.

The term “bimodal polymer” refers to a polymer comprising two mainfractions and more specifically to the form of the polymers molecularweight distribution curve, i.e., the appearance of the graph of thepolymer weight fraction as function of its molecular weight. When themolecular weight distribution curves from these fractions aresuperimposed into the molecular weight distribution curve for the totalresulting polymer product, that curve will show two maxima or at leastbe distinctly broadened in comparison with the curves for the individualfractions. Such a polymer product is called bimodal. It is to be notedhere that also the chemical compositions of the two fractions may bedifferent.

Similarly the term “unimodal polymer” refers to a polymer comprising onemain fraction and more specifically to the form of the polymersmolecular weight distribution curve, i.e., the molecular weightdistribution curve for the total polymer product shows only a singlemaximum.

As used herein, a “blend composition” can be a physical mixture ofcomponents A and B and/or a reaction product produced by a reactionbetween components A and B.

The term “sports equipment” refers to any item of sports equipments suchas sports clothing, boots, sneakers, clogs, sandals, slip on sandals andshoes, golf shoes, tennis shoes, running shoes, athletic shoes, hikingshoes, skis, ski masks, ski boots, cycling shoes, soccer boots, golfclubs, golf bags, and the like.

The present invention can be used in forming golf balls of any desiredsize. “The Rules of Golf” by the USGA dictate that the size of acompetition golf ball must be at least 1.680 inches in diameter;however, golf balls of any size can be used for leisure golf play. Thepreferred diameter of the golf balls is from about 1.680 inches to about1.800 inches. The more preferred diameter is from about 1.680 inches toabout 1.760 inches. A diameter of from about 1.680 inches to about 1.740inches is most preferred; however diameters anywhere in the range offrom 1.70 to about 2.0 inches can be used. Oversize golf balls withdiameters above about 1.760 inches to as big as 2.75 inches are alsowithin the scope of the invention.

Intermediate or Outer Cover Layer

The outer cover and/or one or intermediate layers of the golf balls ofthe present invention includes an ionomer resin. One family of suchresins was developed in the mid-1960's, by E.I. DuPont de Nemours andCo., and is sold under the trademark SURLYN®. Preparation of suchionomers is well known, for example see U.S. Pat. No. 3,264,272.Generally speaking, most commercial ionomers are unimodal and consist ofa polymer of a mono-olefin, e.g., an alkene, with an unsaturated mono-or dicarboxylic acids having 3 to 12 carbon atoms. An additional monomerin the form of a mono- or dicarboxylic acid ester may also beincorporated in the formulation as a so-called “softening comonomer”.The incorporated carboxylic acid groups are then neutralized by a basicmetal ion salt, to form the ionomer. The metal cations of the basicmetal ion salt used for neutralization include Li⁺, Na⁺, K⁺, Zn²⁺, Ca²⁺,Co²⁺, Ni²⁺, Cu²⁺, Pb²⁺, and Mg²⁺, with the Li⁺, Na⁺, Ca²⁺, Zn²⁺, andMg²⁺ being preferred. The basic metal ion salts include those of forexample formic acid, acetic acid, nitric acid, and carbonic acid,hydrogen carbonate salts, oxides, hydroxides, and alkoxides.

The first commercially available ionomer resins contained up to 16weight percent acrylic or methacrylic acid, although it was also wellknown at that time that, as a general rule, the hardness of these covermaterials could be increased with increasing acid content. Hence, inResearch Disclosure 29703, published in January 1989, DuPont disclosedionomers based on ethylene/acrylic acid or ethylene/methacrylic acidcontaining acid contents of greater than 15 weight percent. In this samedisclosure, DuPont also taught that such so called “high acid ionomers”had significantly improved stiffness and hardness and thus could beadvantageously used in golf ball construction, when used either singlyor in a blend with other ionomers.

More recently, high acid ionomers can be ionomer resins with acrylic ormethacrylic acid units present from 16 wt. % to about 35 wt. % in thepolymer. Generally, such a high acid ionomer will have a flexuralmodulus from about 50,000 psi to about 125,000 psi.

Ionomer resins further comprising a softening comonomer, present fromabout 10 wt. % to about 50 wt. % in the polymer, have a flexural modulusfrom about 2,000 psi to about 10,000 psi, and are sometimes referred toas “soft” or “very low modulus” ionomers. Typical softening comonomersinclude n-butyl acrylate, iso-butyl acrylate, n-butyl methacrylate,methyl acrylate and methyl methacrylate.

Today, there are a wide variety of commercially available ionomer resinsbased both on copolymers of ethylene and (meth)acrylic acid orterpolymers of ethylene and (meth)acrylic acid and (meth)acrylate, allof which many of which are be used as a golf ball component. Theproperties of these ionomer resins can vary widely due to variations inacid content, softening comonomer content, the degree of neutralization,and the type of metal ion used in the neutralization. The full rangecommercially available typically includes ionomers of polymers ofgeneral formula, E/X/Y polymer, wherein E is ethylene, X is a C₃ to C₈α,β-ethylenically unsaturated carboxylic acid, such as acrylic ormethacrylic acid, and is present in an amount from about 2 to about 30weight % of the E/X/Y copolymer, and Y is a softening comonomer selectedfrom the group consisting of alkyl acrylate and alkyl methacrylate, suchas methyl acrylate or methyl methacrylate, and wherein the alkyl groupshave from 1-8 carbon atoms, Y is in the range of 0 to about 50 weight %of the E/X/Y copolymer, and wherein the acid groups present in saidionomeric polymer are partially neutralized with a metal selected fromthe group consisting of lithium, sodium, potassium, magnesium, calcium,barium, lead, tin, zinc or aluminum, or a combination of such cations.

The ionomer may also be a so-called bimodal ionomer as described in U.S.Pat. No. 6,562,906 (the entire contents of which are herein incorporatedby reference). These ionomers are bimodal as they are prepared fromblends comprising polymers of different molecular weights. Specificallythey include bimodal polymer blend compositions comprising:

-   -   a) a high molecular weight component having a weight average        molecular weight, Mw, of about 80,000 to about 500,000 and        comprising one or more ethylene/α,β-ethylenically unsaturated        C₃₋₈ carboxylic acid copolymers and/or one or more ethylene,        alkyl(meth)acrylate, (meth)acrylic acid terpolymers; said high        molecular weight component being partially neutralized with        metal ions selected from the group consisting of lithium,        sodium, zinc, calcium, magnesium, and a mixture of any these;        and    -   b) a low molecular weight component having a weight average        molecular weight, Mw, of about from about 2,000 to about 30,000        and comprising one or more ethylene/α,β-ethylenically        unsaturated C₃₋₈ carboxylic acid copolymers and/or one or more        ethylene, alkyl(meth)acrylate, (meth)acrylic acid terpolymers;        said low molecular weight component being partially neutralized        with metal ions selected from the group consisting of lithium,        sodium, potassium, magnesium, calcium, barium, lead, tin, zinc        or aluminum, and a mixture of any these.

In addition to the unimodal and bimodal ionomers, also included are theso-called “modified ionomers” examples of which are described in U.S.Pat. Nos. 6,100,321, 6,329,458 and 6,616,552 and U.S. Patent PublicationUS 2003/0158312 A1, the entire contents of all of which are hereinincorporated by reference.

The modified unimodal ionomers may be prepared by mixing:

-   -   a) an ionomeric polymer comprising ethylene, from 5 to 25 weight        percent (meth)acrylic acid, and from 0 to 40 weight percent of a        (meth)acrylate monomer, said ionomeric polymer neutralized with        metal ions selected from the group consisting of lithium,        sodium, potassium, magnesium, calcium, barium, lead, tin, zinc        or aluminum, and any and all mixtures thereof; and    -   b) from about 5 to about 40 weight percent (based on the total        weight of said modified ionomeric polymer) of one or more fatty        acids or metal salts of said fatty acid, the metal selected from        the group consisting of lithium, sodium, potassium, magnesium,        calcium, barium, lead, tin, zinc or aluminum, and any and all        mixtures thereof; and the fatty acid preferably being stearic        acid.

The modified bimodal ionomers, which are ionomers derived from theearlier described bimodal ethylene/carboxylic acid polymers (asdescribed in U.S. Pat. No. 6,562,906, the entire contents of which areherein incorporated by reference), are prepared by mixing;

-   -   a) a high molecular weight component having a weight average        molecular weight, Mw, of about 80,000 to about 500,000 and        comprising one or more ethylene/α,β-ethylenically unsaturated        C₃₋₈ carboxylic acid copolymers and/or one or more ethylene,        alkyl(meth)acrylate, (meth)acrylic acid terpolymers; said high        molecular weight component being partially neutralized with        metal ions selected from the group consisting of lithium,        sodium, potassium, magnesium, calcium, barium, lead, tin, zinc        or aluminum, and any and all mixtures thereof; and    -   b) a low molecular weight component having a weight average        molecular weight, Mw, of about from about 2,000 to about 30,000        and comprising one or more ethylene/α,β-ethylenically        unsaturated C₃₋₈ carboxylic acid copolymers and/or one or more        ethylene, alkyl(meth)acrylate, (meth)acrylic acid terpolymers;        said low molecular weight component being partially neutralized        with metal ions selected from the group consisting of lithium,        sodium, potassium, magnesium, calcium, barium, lead, tin, zinc        or aluminum, and any and all mixtures thereof; and    -   c) from about 5 to about 40 weight percent (based on the total        weight of said modified ionomeric polymer) of one or more fatty        acids or metal salts of said fatty acid, the metal selected from        the group consisting of lithium, sodium, potassium, magnesium,        calcium, barium, lead, tin, zinc or aluminum, and any and all        mixtures thereof; and the fatty acid preferably being stearic        acid.

The fatty or waxy acid salts utilized in the various modified ionomersare composed of a chain of alkyl groups containing from about 4 to 75carbon atoms (usually even numbered) and characterized by a —COOHterminal group. The generic formula for all fatty and waxy acids aboveacetic acid is CH₃ (CH₂)_(x)COOH, wherein the carbon atom count includesthe carboxyl group (i.e. x=2-73). The fatty or waxy acids utilized toproduce the fatty or waxy acid salts modifiers may be saturated orunsaturated, and they may be present in solid, semi-solid or liquidform.

Examples of suitable saturated fatty acids, i.e., fatty acids in whichthe carbon atoms of the alkyl chain are connected by single bonds,include but are not limited to stearic acid (C₁₈, i.e., CH₃(CH₂)₁₆COOH),palmitic acid (C₁₆, i.e., CH₃(CH₂)₁₄COOH), pelargonic acid (C₉, i.e.,CH₃(CH₂)₇COOH) and lauric acid (C₁₂, i.e., CH₃(CH₂)₁₀OCOOH). Examples ofsuitable unsaturated fatty acids, i.e., a fatty acid in which there areone or more double bonds between the carbon atoms in the alkyl chain,include but are not limited to oleic acid (C₁₃, i.e.,CH₃(CH₂)₇CH:CH(CH₂)₇COOH).

The source of the metal ions used to produce the metal salts of thefatty or waxy acid salts used in the various modified ionomers aregenerally various metal salts which provide the metal ions capable ofneutralizing, to various extents, the carboxylic acid groups of thefatty acids. These include the sulfate, carbonate, acetate andhydroxylate salts of zinc, barium, calcium and magnesium.

Since the fatty acid salts modifiers comprise various combinations offatty acids neutralized with a large number of different metal ions,several different types of fatty acid salts may be utilized in theinvention, including metal stearates, laureates, oleates, andpalmitates, with calcium, zinc, sodium, lithium, potassium and magnesiumstearate being preferred, and calcium and sodium stearate being mostpreferred.

The fatty or waxy acid or metal salt of said fatty or waxy acid ispresent in the modified ionomeric polymers in an amount of from about 5to about 40, preferably from about 7 to about 35, more preferably fromabout 8 to about 20 weight percent (based on the total weight of saidmodified ionomeric polymer).

As a result of the addition of the one or more metal salts of a fatty orwaxy acid, from about 40 to 100, preferably from about 50 to 100, morepreferably from about 70 to 100 percent of the acidic groups in thefinal modified ionomeric polymer composition are neutralized by a metalion.

An example of such a modified ionomer polymer is DuPont® HPF-1000available from E. I. DuPont de Nemours and Co. Inc.

Chelating Agent Salt

We have surprisingly found that the properties of the aforementionedionomeric materials can be modified by blending with a metal or ammoniumsalt of a chelating agent (“CAS”). A chelating agent is typicallydefined as an organic or inorganic compound that will readily bind to ametal ion. Examples of the metal cation in the salts include, but arenot limited to, lithium, calcium, zinc, sodium (including mono sodium,disodium, trisodium and tetrasodium), potassium, magnesium, barium,magnesium, nickel, manganese, or mixtures thereof. Examples of theammonium cation include those having the general formula [NR¹R²R³R⁴]⁺where R¹, R², R³ and R⁴ are selected from the group consisting ofhydrogen, a C₁-C₂₀ aliphatic, cycloaliphatic or aromatic moiety, and anyand all combinations thereof, with the most preferred being the NH₄⁺-salt.

The CAS for use in the golf balls of the present invention, include, butare not limited to, the disodium, trisodium, tetrasodium, dipotassium,tripotassium, dilithium, diammoniumbarium, calcium, cobalt, copper,dysprosium, europium, iron, indium, lanthanum, magnesium, manganese,nickel, samarium, strontium, and zinc salts of chelating agents havingboth amine and carboxylic acid functionality, the so called polyaminocarboxylic acids also known as “complexones”. The polyaminocarboxylates, which have lost acidic protons, form strong complexes withmetal ions by donation of electron pairs from the nitrogen and oxygenatoms to the metal ion to form multiple chelate rings. This propertymakes polyamino carboxylic acids useful in a wide variety of chemical,medical and environmental applications.

The polyamino carboxylic acids from which the the polyamino carboxylatesalts used in the present are derived includeethylenediamine-N,N,N′,N′-tetraacetic acid (EDTA);trans-1,2-diaminocyclohexane-N,N,N′,N′-tetraaceticacid monohydrate;N,N-bis(2-hydroxyethyl)glycine;1,3-diamino-2-hydroxypropane-N,N,N′,N′-tetraacetic acid;1,3-diaminopropane-N,N,N′,N′-tetraacetic acid;ethylenediamine-N,N′-diacetic acid; ethylenediamine-N,N′-dipropionicacid dihydrochloride; ethylenediamine-N,N′-bis(methylenephosphonicacid)hemihydrate; N-(2-hydroxyethyl)ethylenediamine-N,N′,N′-triaceticacid; ethylenediamine-N,N,N′,N′-tetrakis(methylenephosponic acid);O,O′-bis(2-aminoethypethyleneglycol-N,N,N′,N′-tetraacetic acid;N,N-bis(2-hydroxybenzyl-ethylenediamine-N,N-diacetic acid;1,6-hexamethylenediamine-N,N,N′,N′-tetraacetic acid;N-(2-hydroxyethyl)iminodiacetic acid; iminodiacetic acid;1,2-diaminopropane-N,N,N′,N′-tetraacetic acid; nitrilotriacetic acid;nitrilotripropionic acid; the trisodium salt ofnitrilotris(methylenephosphoric acid);7,19,30-trioxa-1,4,10,13,16,22,27,33-octaazabicyclo[11,11,11]pentatriacontanehexahydrobromide; and triethylenetetramine-N,N,N′,N″,N′″,N′″-hexaaceticacid.

More preferably, the polyamino carboxylic acids from which the thepolyamino carboxylate salts used in the present are derived includeethylenediamine-N,N,N′,N′-tetraacetic acid (EDTA); the disodium,trisodium, tetrasodium, dipotassium, tripotassium, dilithium anddiammonium salts of EDTA;1,3-diamino-2-hydroxypropane-N,N,N′,N′-tetraacetic acid;1,3-diaminopropane-N,N,N′,N′-tetraacetic acid;O,O′-bis(2-aminoethypethyleneglycol-N,N,N′,N′-tetraacetic acid; and7,19,30-trioxa-1,4,10,13,16,22,27,33-octaazabicyclo[11,11,11]pentatriacontanehexahydrobromide.

The disodium salt, tetrasodium salt and monocalcium disodium salt ofEDTA are most preferred.

According to another embodiment, the CAS for use in the golf balls ofthe present invention may be the metal and/or ammonium salt of anunsaturated poly(carboxylic acid). The term “unsaturated' refers to atleast one carbon to carbon unsaturated bond. The poly(carboxylic acid)salt is distinct from the polymers described as ionomers in the presentapplication. In particular, the poly(carboxylic acid) salt is derived(i.e., produced) from an unsaturated mono- or dicarboxylic acid having 3to 12 carbon atoms, but they are not also derived (i.e., produced) froma polymer of a mono-olefin or α-olefin, e.g., an alkene.

Unsaturated polymeric carboxylic acid salts for use as the CAS of thepresent invention include, but are not limited to, the metal or ammoniumsalts of poly(acrylic), poly(methacrylic), poly(ethacrylic),poly(α-chloroacrylic), poly(crotonic), poly(maleic), poly(fumaric),poly(itaconic) acids with the metal or ammonium salts of poly(acrylicacid) (PAA) or poly(methacrylic acid) (PMAA) being most preferred. Theexamples of the metal cation in the salts include, but are not limitedto, lithium, calcium, zinc, sodium, potassium, magnesium, barium,magnesium, nickel, manganese, or mixtures thereof. The preferred metalsalt used in this invention is sodium. Examples of the ammonium cationinclude those having the general formula [NR¹R²R³R⁴]⁺ where R¹, R², R³and R⁴ are selected from the group consisting of hydrogen, a C₁-C₂₀aliphatic, cycloaliphatic or aromatic moiety, and any and allcombinations thereof, with the most preferred being the NH₄ ⁺-salt.

Additional Polymer Components

In addition to the modified ionomers of the present invention, otherpolymeric materials generally considered useful for making golf ballsmay also be included as either an additional blend component of themodified ionomer composition or as one or more of the components of thegolf balls of the present invention. These include, without limitation,synthetic and natural rubbers, thermoset polymers such as otherthermoset polyurethanes or thermoset polyureas, as well as thermoplasticpolymers including thermoplastic elastomers such as metallocenecatalyzed polymer, unimodal ethylene/carboxylic acid copolymers,unimodal ethylene/carboxylic acid/carboxylate terpolymers, bimodalethylene/carboxylic acid copolymers, bimodal ethylene/carboxylicacid/carboxylate terpolymers, thermoplastic polyurethanes, thermoplasticpolyureas, polyamides, copolyamides, polyesters, copolyesters,polycarbonates, polyolefins, halogenated (e.g. chlorinated) polyolefins,halogenated polyalkylene compounds, such as halogenated polyethylene[e.g. chlorinated polyethylene (CPE)], polyalkenamer, polyphenyleneoxides, polyphenylene sulfides, diallyl phthalate polymers, polyimides,polyvinyl chlorides, polyamide-ionomers, polyurethane-ionomers,polyvinyl alcohols, polyarylates, polyacrylates, polyphenylene ethers,impact-modified polyphenylene ethers, polystyrenes, high impactpolystyrenes, acrylonitrile-butadiene-styrene copolymers,styrene-acrylonitriles (SAN), acrylonitrile-styrene-acrylonitriles,styrene-maleic anhydride (S/MA) polymers, styrenic block copolymersincluding styrene-butadiene-styrene (SBS),styrene-ethylene-butylene-styrene, (SEBS) andstyrene-ethylene-propylene-styrene (SEPS), styrenic terpolymers,functionalized styrenic block copolymers including hydroxylated,functionalized styrenic copolymers, and terpolymers, cellulosicpolymers, liquid crystal polymers (LCP), ethylene-propylene-dieneterpolymers (EPDM), ethylene-vinyl acetate copolymers (EVA),ethylene-propylene copolymers, propylene elastomers (such as thosedescribed in U.S. Pat. No. 6,525,157, to Kim et al, the entire contentsof which is hereby incorporated by reference in its entirety), ethylenevinyl acetates, polyureas, and polysiloxanes and any and allcombinations thereof.

One preferred material which may be used as a component of the coverlayer or intermediate layer of the golf balls of the present inventioncomprises a blend of an ionomer and a block copolymer. Examples of suchblock copolymers include styrenic block copolymers includingstyrene-butadiene-styrene (SBS), styrene-ethylene-butylene-styrene,(SEBS) and styrene-ethylene/propylene-styrene (SEPS). Also included arefunctionalized styrenic block copolymers, including those where theblock copolymer incorporates a first polymer block having an aromaticvinyl compound, a second polymer block having a conjugated dienecompound and a hydroxyl group located at a block copolymer, or itshydrogenation product, and in which the ratio of block copolymer toionomer ranges from 5:95 to 95:5 by weight, more preferably from about10:90 to about 90:10 by weight, more preferably from about 20:80 toabout 80:20 by weight, more preferably from about 30:70 to about 70:30by weight and most preferably from about 35:65 to about 65:35 by weight.A preferred functionalized styrenic block copolymer is SEPTON HG-252.Such blends are described in more detail in commonly-assigned U.S. Pat.No. 6,861,474 and U.S. Patent Publication No. 2003/0224871 both of whichare incorporated herein by reference in their entireties.

Another preferred material for either the outer cover and/or one orintermediate layers of the golf balls of the present invention is acomposition prepared by blending together at least three materials,identified as Components A, B, and C, and melt-processing thesecomponents to form in-situ, a polymer blend composition incorporating apseudo-crosslinked polymer network. Such blends are described in moredetail in commonly-assigned U.S. Pat. No. 6,930,150, to Kim et al, thecontent of which is incorporated by reference herein in its entirety.Component A is a monomer, oligomer, prepolymer or polymer thatincorporates at least five percent by weight of at least one type of anacidic functional group. Examples of such polymers suitable for use asinclude, but are not limited to, ethylene/(meth)acrylic acid copolymersand ethylene/(meth)acrylic acid/alkyl(meth)acrylate terpolymers, orethylene and/or propylene maleic anhydride copolymers and terpolymers.Examples of such polymers which are commercially available include, butare not limited to, the Escor® 5000, 5001, 5020, 5050, 5070, 5100, 5110and 5200 series of ethylene-acrylic acid copolymers sold by Exxon andthe PRIMACOR® 1321, 1410, 1410-XT, 1420, 1430, 2912, 3150, 3330, 3340,3440, 3460, 4311, 4608 and 5980 series of ethylene-acrylic acidcopolymers sold by The Dow Chemical Company, Midland, Mich. and theethylene-acrylic acid copolymers Nucrel 599, 699, 0903, 0910, 925, 960,2806, and 2906 ethylene-methacrylic acid copolymers. sold by DuPont Alsoincluded are the bimodal ethylene/carboxylic acid polymers as describedin U.S. Pat. No. 6,562,906, the contents of which are incorporatedherein by reference. These polymers comprise ethylene/α,β-ethylenicallyunsaturated C₃₋₈ carboxylic acid high copolymers, particularlyethylene(meth)acrylic acid copolymers and ethylene, alkyl(meth)acrylate,(meth)acrylic acid terpolymers, having molecular weights of about 80,000to about 500,000 which are melt blended with ethylene/α,β-ethylenicallyunsaturated C₃₋₈ carboxylic acid copolymers, particularlyethylene/(meth)acrylic acid copolymers having molecular weights of about2,000 to about 30,000.

Component B can be any monomer, oligomer, or polymer, preferably havinga lower weight percentage of anionic functional groups than that presentin Component A in the weight ranges discussed above, and most preferablyfree of such functional groups. Examples of materials for use asComponent B include block copolymers such as styrenic block copolymersincluding styrene-butadiene-styrene (SBS),styrene-ethylene-butylene-styrene, (SEBS) andstyrene-ethylene/propylene-styrene (SEPS). Also included arefunctionalized styrenic block copolymers, including those where theblock copolymer incorporates a first polymer block having an aromaticvinyl compound, a second polymer block having a conjugated dienecompound and a hydroxyl group located at a block copolymer, or itshydrogenation product. Commercial examples SEPTON marketed by KurarayCompany of Kurashiki, Japan; TOPRENE by Kumho Petrochemical Co., Ltd andKRATON marketed by Kraton Polymers.

Component C is a base capable of neutralizing the acidic functionalgroup of Component A and is a base having a metal cation. These metalsare from groups IA, IB, IIA, IIB, IIIA, IIIB, IVA, IVB, VA, VB, VIA,VIB, VIIB and VIIIB of the periodic table. Examples of these metalsinclude lithium, sodium, magnesium, aluminum, potassium, calcium,manganese, tungsten, titanium, iron, cobalt, nickel, hafnium, copper,zinc, barium, zirconium, and tin. Suitable metal compounds for use as asource of Component C are, for example, metal salts, preferably metalhydroxides, metal oxides, metal carbonates, or metal acetates.

The composition preferably is prepared by mixing the above materialsinto each other thoroughly, either by using a dispersive mixingmechanism, a distributive mixing mechanism, or a combination of these.These mixing methods are well known in the manufacture of polymerblends. As a result of this mixing, the anionic functional group ofComponent A is dispersed evenly throughout the mixture. Most preferably,Components A and B are melt-mixed together without Component C, with orwithout the premixing discussed above, to produce a melt-mixture of thetwo components. Then, Component C separately is mixed into the blend ofComponents A and B. This mixture is melt-mixed to produce the reactionproduct. This two-step mixing can be performed in a single process, suchas, for example, an extrusion process using a proper barrel length orscrew configuration, along with a multiple feeding system.

Another preferred material which may be used as a component of the coverlayer or intermediate layer of the golf balls of the present inventionare the polyalkenamers which may be prepared by ring opening metathesispolymerization of one or more cycloalkenes in the presence oforganometallic catalysts as described in U.S. Pat. Nos. 3,492,245, and3,804,803, the entire contents of both of which are herein incorporatedby reference. Examples of suitable polyalkenamer rubbers arepolybutenamer rubber, polypentenamer rubber, polyhexenamer rubber,polyheptenamer rubber, polyoctenamer rubber, polynonenamer rubber,polydecenamer rubber polyundecenamer rubber, polydodecenamer rubber,polytridecenamer rubber. For further details concerning polyalkenamerrubber, see Rubber Chem. & Tech., Vol. 47, page 511-596, 1974, which isincorporated herein by reference. Polyoctenamer rubbers are commerciallyavailable from Huls A G of Marl, Germany, and through its distributor inthe U.S., Creanova Inc. of Somerset, N.J., and sold under the trademarkVESTENAMER®. Two grades of the VESTENAMER® trans-polyoctenamer arecommercially available: VESTENAMER 8012 designates a material having atrans-content of approximately 80% (and a cis-content of 20%) with amelting point of approximately 54° C.; and VESTENAMER 6213 designates amaterial having a trans-content of approximately 60% (cis-content of40%) with a melting point of approximately 30° C. Both of these polymershave a double bond at every eighth carbon atom in the ring.

The polyalkenamer rubbers used in the present disclosure exhibitexcellent melt processability above their sharp melting temperatures andexhibit high miscibility with various rubber additives as a majorcomponent without deterioration of crystallinity which in turnfacilitates injection molding. Thus, unlike synthetic polybutadienerubbers typically used in golf ball core preparation, injection moldedparts of polyalkenamer-based compounds can be prepared which, inaddition, can also be partially or fully crosslinked at elevatedtemperature. The crosslinked polyalkenamer compounds are highly elastic,and their mechanical and physical properties can be easily modified byadjusting the formulation.

The polyalkenamer composition surprisingly exhibits superiorcharacteristics over a broad spectrum of properties that relate to theeffectiveness of a composition for use in the SCR of the golf balls ofthe present invention. For example, the composition exhibits superiorimpact durability and Coefficient of Restitution (COR) in apre-determined hardness range (e.g., a hardness Shore D of from about 15to about 85, preferably from about 40 to about 80, and more preferablyfrom about 40 to about 75. More particularly, the compositions disclosedherein exhibit excellent hardness adjustment without significantlycompromising COR or processability.

The polyalkenamer rubbers may also be blended within other polymers andan especially preferred blend is that of a polyalkenamer and apolyamide. A more complete description of the polyalkenamer rubbers aredisclosed in U.S. Pat. No. 7,528,196 and copending U.S. application Ser.No. 12/415,522, filed on Mar. 31, 2009, both in the name of Hyun Kim etal., the entire contents of both of which are hereby incorporated byreference.

The polyalkenamer rubber preferably contains from about 50 to about 99,preferably from about 60 to about 99, more preferably from about 65 toabout 99, even more preferably from about 70 to about 90 percent of itsdouble bonds in the trans-configuration. The preferred form of thepolyalkenamer has a trans content of approximately 80%, however,compounds having other ratios of the cis- and trans-isomeric forms ofthe polyalkenamer can also be obtained by blending available productsfor use in making the composition.

The polyalkenamer rubber has a molecular weight (as measured by GPC)from about 10,000 to about 300,000, preferably from about 20,000 toabout 250,000, more preferably from about 30,000 to about 200,000, evenmore preferably from about 50,000 to about 150,000.

The polyalkenamer rubber has a degree of crystallization (as measured byDSC secondary fusion) from about 5 to about 70, preferably from about 6to about 50, more preferably from about from 6.5 to about 50%, even morepreferably from about from 7 to about 45%.

More preferably, the polyalkenamer rubber is a polymer prepared bypolymerization of cyclooctene to form a trans-polyoctenamer rubber as amixture of linear and cyclic macromolecules.

Another preferred material for the outer cover and/or one orintermediate layers of the golf balls of the present invention is ablend of a homopolyamide or copolyamide modified and a polymer includinga grafted maleic anhydride group.

Another preferred material which may be used as a component of the coverlayer or intermediate layer of the golf balls of the present inventionis the family of polyurethanes or polyureas which are typically areprepared by reacting a diisocyanate with a polyol (in the case ofpolyurethanes) or with a polyamine (in the case of a polyurea).Thermoplastic polyurethanes or polyureas may consist solely of thisinitial mixture or may be further combined with a chain extender to varyproperties such as hardness of the thermoplastic. Thermosetpolyurethanes or polyureas typically are formed by the reaction of adiisocyanate and a polyol or polyamine respectively, and an additionalcrosslinking agent to crosslink or cure the material to result in athermoset.

In what is known as a one-shot process, the three reactants,diisocyanate, polyol or polyamine, and optionally a chain extender or acuring agent, are combined in one step. Alternatively, a two-stepprocess may occur in which the first step involves reacting thediisocyanate and the polyol (in the case of polyurethane) or thepolyamine (in the case of a polyurea) to form a so-called prepolymer, towhich can then be added either the chain extender or the curing agent.This procedure is known as the prepolymer process.

In addition, although depicted as discrete component packages as above,it is also possible to control the degree of crosslinking, and hence thedegree of thermoplastic or thermoset properties in a final composition,by varying the stoichiometry not only of the diisocyanate-to-chainextender or curing agent ratio, but also the initialdiisocyanate-to-polyol or polyamine ratio. Of course in the prepolymerprocess, the initial diisocyanate-to-polyol or polyamine ratio is fixedon selection of the required prepolymer.

In addition to discrete thermoplastic or thermoset materials, it also ispossible to modify a thermoplastic polyurethane or polyurea compositionby introducing materials in the composition that undergo subsequentcuring after molding the thermoplastic to provide properties similar tothose of a thermoset. For example, Kim in U.S. Pat. No. 6,924,337, theentire contents of which are hereby incorporated by reference, disclosesa thermoplastic urethane or urea composition optionally comprising chainextenders and further comprising a peroxide or peroxide mixture, whichcan then undergo post curing to result in a thermoset.

Also, Kim et al. in U.S. Pat. No. 6,939,924, the entire contents ofwhich are hereby incorporated by reference, discloses a thermoplasticurethane or urea composition, optionally also comprising chainextenders, that are prepared from a diisocyanate and a modified orblocked diisocyanate which unblocks and induces further cross linkingpost extrusion. The modified isocyanate preferably is selected from thegroup consisting of: isophorone diisocyanate (IPDI)-based uretdione-typecrosslinker; a combination of a uretdione adduct of IPDI and a partiallye-caprolactam-modified IPDI; a combination of isocyanate adductsmodified by e-caprolactam and a carboxylic acid functional group; acaprolactam-modified Desmodur diisocyanate; a Desmodur diisocyanatehaving a 3,5-dimethyl pyrazole modified isocyanate; or mixtures ofthese.

Finally, Kim et al. in U.S. Pat. No. 7,037,985 B2, the entire contentsof which are hereby incorporated by reference, discloses thermoplasticurethane or urea compositions further comprising a reaction product of anitroso compound and a diisocyanate or a polyisocyanate. The nitrosoreaction product has a characteristic temperature at which it decomposesto regenerate the nitroso compound and diisocyanate or polyisocyanate.Thus, by judicious choice of the post-processing temperature, furthercrosslinking can be induced in the originally thermoplastic compositionto provide thermoset-like properties.

Any isocyanate available to one of ordinary skill in the art is suitablefor use according to the invention. Isocyanates for use with the presentinvention include, but are not limited to, aliphatic, cycloaliphatic,aromatic aliphatic, aromatic, any derivatives thereof, and combinationsof these compounds having two or more isocyanate (NCO) groups permolecule. As used herein, aromatic aliphatic compounds should beunderstood as those containing an aromatic ring, wherein the isocyanategroup is not directly bonded to the ring. One example of an aromaticaliphatic compound is a tetramethylene diisocyanate (TMXDI). Theisocyanates may be organic polyisocyanate-terminated prepolymers, lowfree isocyanate prepolymer, and mixtures thereof. Theisocyanate-containing reactable component also may include anyisocyanate-functional monomer, dimer, trimer, or polymeric adductthereof, prepolymer, quasi-prepolymer, or mixtures thereof.Isocyanate-functional compounds may include monoisocyanates orpolyisocyanates that include any isocyanate functionality of two ormore.

Suitable isocyanate-containing components include diisocyanates havingthe generic structure: O═C═N—R—N═C═O, where R preferably is a cyclic,aromatic, or linear or branched hydrocarbon moiety containing from about1 to about 50 carbon atoms. The isocyanate also may contain one or morecyclic groups or one or more phenyl groups. When multiple cyclic oraromatic groups are present, linear and/or branched hydrocarbonscontaining from about 1 to about 10 carbon atoms can be present asspacers between the cyclic or aromatic groups. In some cases, the cyclicor aromatic group(s) may be substituted at the 2-, 3-, and/or4-positions, or at the ortho-, meta-, and/or para-positions,respectively. Substituted groups may include, but are not limited to,halogens, primary, secondary, or tertiary hydrocarbon groups, or amixture thereof.

Examples of isocyanates that can be used with the present inventioninclude, but are not limited to, substituted and isomeric mixturesincluding 2,2′-, 2,4′-, and 4,4′-diphenylmethane diisocyanate (MDI);3,3′-dimethyl-4,4′-biphenylene diisocyanate (TODD; toluene diisocyanate(TDI); polymeric MDI; carbodiimide-modified liquid 4,4′-diphenylmethanediisocyanate; para-phenylene diisocyanate (PPDI); meta-phenylenediisocyanate (MPDI); triphenyl methane-4,4′- and triphenylmethane-4,4″-triisocyanate; naphthylene-1,5-diisocyanate; 2,4′-, 4,4′-,and 2,2-biphenyl diisocyanate; polyphenylene polymethylenepolyisocyanate (PMDI) (also known as polymeric PMDI); mixtures of MDIand PMDI; mixtures of PMDI and TDI; ethylene diisocyanate;propylene-1,2-diisocyanate; trimethylene diisocyanate; butylenesdiisocyanate; bitolylene diisocyanate; tolidine diisocyanate;tetramethylene-1,2-diisocyanate; tetramethylene-1,3-diisocyanate;tetramethylene-1,4-diisocyanate; pentamethylenediisocyanate;1,6-hexamethylene diisocyanate (HDI); octamethylenediisocyanate; decamethylene diisocyanate; 2,2,4-trimethylhexamethylenediisocyanate; 2,4,4-trimethylhexamethylene diisocyanate;dodecane-1,12-diisocyanate; dicyclohexylmethane diisocyanate;cyclobutane-1,3-diisocyanate; cyclohexane-1,2-diisocyanate;cyclohexane-1,3-diisocyanate; cyclohexane-1,4-diisocyanate; diethylidenediisocyanate; methylcyclohexylene diisocyanate (HTDI);2,4-methylcyclohexane diisocyanate; 2,6-methylcyclohexane diisocyanate;4,4′-dicyclohexyl diisocyanate; 2,4′-dicyclohexyl diisocyanate;1,3,5-cyclohexane triisocyanate; isocyanatomethylcyclohexane isocyanate;1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane;isocyanatoethylcyclohexane isocyanate; bis(isocyanatomethyl)-cyclohexanediisocyanate; 4,4′-bis(isocyanatomethyl)dicyclohexane;2,4′-bis(isocyanatomethyl)dicyclohexane; isophorone diisocyanate (IPDI);dimeryl diisocyanate, dodecane-1,12-diisocyanate, 1,10-decamethylenediisocyanate, cyclohexylene-1,2-diisocyanate, 1,10-decamethylenediisocyanate, 1-chlorobenzene-2,4-diisocyanate, furfurylidenediisocyanate, 2,4,4-trimethyl hexamethylene diisocyanate,2,2,4-trimethyl hexamethylene diisocyanate, dodecamethylenediisocyanate, 1,3-cyclopentane diisocyanate, 1,3-cyclohexanediisocyanate, 1,3-cyclobutane diisocyanate, 1,4-cyclohexanediisocyanate, 4,4′-methylenebis(cyclohexyl isocyanate),4,4′-methylenebis(phenyl isocyanate), 1-methyl-2,4-cyclohexanediisocyanate, 1-methyl-2,6-cyclohexane diisocyanate,1,3-bis(isocyanato-methyl)cyclohexane,1,6-diisocyanato-2,2,4,4-tetra-methylhexane,1,6-diisocyanato-2,4,4-tetra-trimethylhexane,trans-cyclohexane-1,4-diisocyanate,3-isocyanato-methyl-3,5,5-trimethylcyclo-hexyl isocyanate,1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane, cyclohexylisocyanate, dicyclohexylmethane 4,4′-diisocyanate,1,4-bis(isocyanatomethyl)cyclohexane, m-phenylene diisocyanate,m-xylylene diisocyanate, m-tetramethylxylylene diisocyanate, p-phenylenediisocyanate, p,p′-biphenyl diisocyanate, 3,3′-dimethyl-4,4′-biphenylenediisocyanate, 3,3′-dimethoxy-4,4′-biphenylene diisocyanate,3,3′-diphenyl-4,4′-biphenylene diisocyanate, 4,4′-biphenylenediisocyanate, 3,3′-dichloro-4,4′-biphenylene diisocyanate,1,5-naphthalene diisocyanate, 4-chloro-1,3-phenylene diisocyanate,1,5-tetrahydronaphthalene diisocyanate, metaxylene diisocyanate,2,4-toluene diisocyanate, 2,4′-diphenylmethane diisocyanate,2,4-chlorophenylene diisocyanate, 4,4′-diphenylmethane diisocyanate,p,p′-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate,2,6-tolylene diisocyanate, 2,2-diphenylpropane-4,4′-diisocyanate,4,4′-toluidine diisocyanate, dianidine diisocyanate, 4,4′-diphenyl etherdiisocyanate, 1,3-xylylene diisocyanate, 1,4-naphthylene diisocyanate,azobenzene-4,4′-diisocyanate, diphenyl sulfone-4,4′-diisocyanate,triphenylmethane 4,4′,4″-triisocyanate, isocyanatoethyl methacrylate,3-isopropenyl-α,α-dimethylbenzyl-isocyanate, dichiorohexamethylenediisocyanate, ω,ω′-diisocyanato-1,4-diethylbenzene, polymethylenepolyphenylene polyisocyanate, isocyanurate modified compounds, andcarbodiimide modified compounds, as well as biuret modified compounds ofthe above polyisocyanates. These isocyanates may be used either alone orin combination. These combination isocyanates include triisocyanates,such as biuret of hexamethylene diisocyanate and triphenylmethanetriisocyanates, and polyisocyanates, such as polymeric diphenylmethanediisocyanate.triisocyanate of HDI; triisocyanate of2,2,4-trimethyl-1,6-hexane diisocyanate (TMDI); 4,4′-dicyclohexylmethanediisocyanate (H₁₂MDI); 2,4-hexahydrotoluene diisocyanate;2,6-hexahydrotoluene diisocyanate; 1,2-, 1,3-, and 1,4-phenylenediisocyanate; aromatic aliphatic isocyanate, such as 1,2-, 1,3-, and1,4-xylene diisocyanate; meta-tetramethylxylene diisocyanate (m-TMXDI);para-tetramethylxylene diisocyanate (p-TMXDI); trimerized isocyanurateof any polyisocyanate, such as isocyanurate of toluene diisocyanate,trimer of diphenylmethane diisocyanate, trimer of tetrannethylxylenediisocyanate, isocyanurate of hexamethylene diisocyanate, and mixturesthereof, dimerized uretdione of any polyisocyanate, such as uretdione oftoluene diisocyanate, uretdione of hexamethylene diisocyanate, andmixtures thereof; modified polyisocyanate derived from the aboveisocyanates and polyisocyanates; and mixtures thereof.

Any polyol now known or hereafter developed is suitable for useaccording to the invention. Polyols suitable for use in the presentinvention include, but are not limited to, polyester polyols, polyetherpolyols, polycarbonate polyols and polydiene polyols such aspolybutadiene polyols.

Any polyamine available to one of ordinary skill in the polyurethane artis suitable for use according to the invention. Polyamines suitable foruse in the compositions of the present invention include, but are notlimited to, amine-terminated compounds typically are selected fromamine-terminated hydrocarbons, amine-terminated polyethers,amine-terminated polyesters, amine-terminated polycaprolactones,amine-terminated polycarbonates, amine-terminated polyamides, andmixtures thereof. The amine-terminated compound may be a polyether amineselected from polytetramethylene ether diamines, polyoxypropylenediamines, poly(ethylene oxide capped oxypropylene)ether diamines,triethyleneglycoldiamines, propylene oxide-based triamines,trimethylolpropane-based triamines, glycerin-based triamines, andmixtures thereof.

The diisocyanate and polyol or polyamine components may be combined toform a prepolymer prior to reaction with a chain extender or curingagent. Any such prepolymer combination is suitable for use in thepresent invention.

One preferred prepolymer is a toluene diisocyanate prepolymer withpolypropylene glycol. Such polypropylene glycol terminated toluenediisocyanate prepolymers are available from Uniroyal Chemical Company ofMiddlebury, Conn., under the trade name ADIPRENE® LFG963A and LFG640D.Most preferred prepolymers are the polytetramethylene ether glycolterminated toluene diisocyanate prepolymers including those availablefrom Uniroyal Chemical Company of Middlebury, Conn., under the tradename ADIPRENE® LF930A, LF950A, LF601D, and LF751D.

In one embodiment, the number of free NCO groups in the urethane or ureaprepolymer may be less than about 14 percent. Preferably the urethane orurea prepolymer has from about 3 percent to about 11 percent, morepreferably from about 4 to about 9.5 percent, and even more preferablyfrom about 3 percent to about 9 percent, free NCO on an equivalentweight basis.

Polyol chain extenders or curing agents may be primary, secondary, ortertiary polyols. Non-limiting examples of monomers of these polyolsinclude: trimethylolpropane (TMP), ethylene glycol, 1,3-propanediol,1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, propylene glycol,dipropylene glycol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol,1,2-pentanediol, 2,3-pentanediol, 2,5-hexanediol, 2,4-hexanediol,2-ethyl-1,3-hexanediol, cyclohexanediol, and2-ethyl-2-(hydroxymethyl)-1,3-propanediol.

Diamines and other suitable polyamines may be added to the compositionsof the present invention to function as chain extenders or curingagents. These include primary, secondary and tertiary amines having twoor more amines as functional groups. Exemplary diamines includealiphatic diamines, such as tetramethylenediamine,pentamethylenediamine, hexamethylenediamine; alicyclic diamines, such as3,3′-dimethyl-4,4′-diamino-dicyclohexyl methane; or aromatic diamines,such as diethyl-2,4-toluenediamine, 4,4″-methylenebis-(3-chloro,2,6-diethyl)-aniline (available from Air Products and Chemicals Inc., ofAllentown, Pa., under the trade name LONZACURE®),3,3′-dichlorobenzidene; 3,3′-dichloro-4,4′-diaminodiphenyl methane(MOCA); N,N,N′,N′-tetrakis(2-hydroxyproml)ethylenediamine,3,5-dimethylthio-2,4-toluenediamine;3,5-dimethylthio-2,6-toluenediamine; N,N′-dialkyldiamino diphenylmethane; trimethylene-glycol-di-p-aminobenzoate;polytetramethyleneoxide-di-p-aminobenzoate, 4,4′-methylenebis-2-chloroaniline, 2,2′,3,3′-tetrachloro-4,4′-diamino-phenyl methane,p,p′-methylenedianiline, p-phenylenediamine or 4,4′-diaminodiphenyl; and2,4,6-tris(dimethylaminomethyl) phenol.

Depending on their chemical structure, curing agents may be slow- orfast-reacting polyamines or polyols. As described in U.S. Pat. Nos.6,793,864, 6,719,646 and copending U.S. Patent Publication No.2004/0201133 A1, (the contents of all of which are hereby incorporatedherein by reference), slow-reacting polyamines are diamines having aminegroups that are sterically and/or electronically hindered by electronwithdrawing groups or bulky groups situated proximate to the aminereaction sites. The spacing of the amine reaction sites will also affectthe reactivity speed of the polyamines.

Suitable curatives for use in the present invention are selected fromthe slow-reacting polyamine group include, but are not limited to,3,5-dimethylthio-2,4-toluenediamine;3,5-dimethylthio-2,6-toluenediamine; N,N′-dialkyldiamino diphenylmethane; trimethylene-glycol-di-p-aminobenzoate;polytetramethyleneoxide-di-p-aminobenzoate, and mixtures thereof. Ofthese, 3,5-dimethylthio-2,4-toluenediamine and3,5-dimethylthio-2,6-toluenediamine are isomers and are sold under thetrade name ETHACURE® 300 by Ethyl Corporation. Trimethyleneglycol-di-p-aminobenzoate is sold under the trade name POLACURE 740M andpolytetramethyleneoxide-di-p-aminobenzoates are sold under the tradename POLAMINES by Polaroid Corporation. N,N′-dialkyldiamino diphenylmethane is sold under the trade name UNILINK® by UOP.

Also included as a curing agent for use in the polyurethane or polyureacompositions used in the present invention are the family ofdicyandiamides as described in copending application Ser. No. 11/809,432filed on May 31, 2007 by Kim et al., the entire contents of which arehereby incorporated by reference

The modified ionomer composition used to prepare the golf ball coverand/or at least one intermediate layer can be prepared directly bymixing the individual blend components or in-situ by combining the baseionomer precursors, any additional blend components and the CAS in anyand all combinations including;

-   -   1) Mixing the ionomer composition with the CAS after which        optionally additional non-ionomeric polymer components may be        added;    -   2) Mixing the ionomer composition with optionally any additional        non-ionomeric polymer components and then blending this mixture        with the CAS;    -   3) Mixing the ionomer precursor of an ethylene/α,β-ethylenically        unsaturated C₃₋₈ carboxylic acid copolymer and/or one or more        ethylene, alkyl(meth)acrylate, (meth)acrylic acid terpolymer        with optionally additional non-ionomeric polymer components        which mixture can then be mixed with the CAS either prior to, or        with, subsequent neutralization of the ionomer precursor by for        example acetate, oxide or hydroxide salts of lithium, calcium,        zinc, sodium, potassium, magnesium, magnesium, nickel,        manganese, or mixtures thereof.

Core Composition

The cores of the golf balls of the present invention may include thetraditional rubber components used in golf ball applications including,both natural and synthetic rubbers, such as cis-1,4-polybutadiene,trans-1,4-polybutadiene, 1,2-polybutadiene, cis-polyisoprene,trans-polyisoprene, polychloroprene, polybutylene, styrene-butadienerubber, styrene-butadiene-styrene block copolymer and partially andfully hydrogenated equivalents, styrene-isoprene-styrene block copolymerand partially and fully hydrogenated equivalents, nitrile rubber,silicone rubber, and polyurethane, as well as mixtures of these.Polybutadiene rubbers, especially 1,4-polybutadiene rubbers containingat least 40 mol %, and more preferably 80 to 100 mol % of cis-1,4 bonds,are preferred because of their high rebound resilience, moldability, andhigh strength after vulcanization. The polybutadiene component may besynthesized by using rare earth-based catalysts, nickel-based catalysts,or cobalt-based catalysts, conventionally used in this field.Polybutadiene obtained by using lanthanum rare earth-based catalystsusually employ a combination of a lanthanum rare earth (atomic number of57 to 71)-compound, but particularly preferred is a neodymium compound.

The 1,4-polybutadiene rubbers have a molecular weight distribution(Mw/Mn) of from about 1.2 to about 4.0, preferably from about 1.7 toabout 3.7, even more preferably from about 2.0 to about 3.5, mostpreferably from about 2.2 to about 3.2. The polybutadiene rubbers have aMooney viscosity (ML₁₊₄(100° C.)) of from about 20 to about 80,preferably from about 30 to about 70, even more preferably from about 30to about 60, most preferably from about 35 to about 50. The term “Mooneyviscosity” used herein refers in each case to an industrial index ofviscosity as measured with a Mooney viscometer, which is a type ofrotary plastometer (see JIS K6300). This value is represented by thesymbol ML₁₊₄(100° C.), wherein “M” stands for Mooney viscosity, “L”stands for large rotor (L-type), “1+4” stands for a pre-heating time of1 minute and a rotor rotation time of 4 minutes, and “100° C.” indicatesthat measurement was carried out at a temperature of 100° C. As readilyappreciated by one skilled in the art, blends of polybutadiene rubbersmay also be utilized in the golf balls of the present invention, suchblends may be prepared with any mixture of rare earth-based catalysts,nickel-based catalysts, or cobalt-based catalysts derived materials, andfrom materials having different molecular weights, molecular weightdistributions and Mooney viscosity.

The cores of the golf balls of the present invention may also include1,2-polybutadienes having differing tacticity, all of which are suitableas unsaturated polymers for use in the presently disclosed compositions,are atactic 1,2-polybutadiene, isotactic 1,2-polybutadiene, andsyndiotactic 1,2-polybutadiene. Syndiotactic 1,2-polybutadiene havingcrystallinity suitable for use as an unsaturated polymer in thepresently disclosed compositions are polymerized from a 1,2-addition ofbutadiene. The presently disclosed golf balls may include syndiotactic1,2-polybutadiene having crystallinity and greater than about 70% of1,2-bonds, more preferably greater than about 80% of 1,2-bonds, and mostpreferably greater than about 90% of 1,2-bonds. Also, the1,2-polybutadiene may have a mean molecular weight between about 10,000and about 350,000, more preferably between about 50,000 and about300,000, more preferably between about 80,000 and about 200,000, andmost preferably between about 10,000 and about 150,000. Examples ofsuitable syndiotactic 1,2-polybutadienes having crystallinity suitablefor use in golf balls are sold under the trade names RB810, RB820, andRB830 by JSR Corporation of Tokyo, Japan.

The cores of the golf balls of the present invention may also includethe polyalkenamer rubbers as previously described herein and disclosedin copending U.S. application Ser. No. 11/335,070, filed on Jan. 18,2006, in the name of Hyun Kim et al., the entire contents of which arehereby incorporated by reference.

When synthetic rubbers such as the aforementioned polybutadienes orpolyalkenamers and their blends are used in the golf balls of thepresent invention they may contain further materials typically oftenused in rubber formulations including crosslinking agents,co-crosslinking agents, peptizers and accelerators.

Suitable cross-linking agents for use in the golf balls of the presentinvention include peroxides, sulfur compounds, or other known chemicalcross-linking agents, as well as mixtures of these. Non-limitingexamples of suitable cross-linking agents include primary, secondary, ortertiary aliphatic or aromatic organic peroxides. Peroxides containingmore than one peroxy group can be used, such as2,5-dimethyl-2,5-di(tert-butylperoxy)hexane and 1,4-di-(2-tert-butylperoxyisopropyl)benzene. Both symmetrical and asymmetrical peroxides canbe used, for example, tert-butyl perbenzoate and tert-butyl cumylperoxide. Peroxides incorporating carboxyl groups also are suitable. Thedecomposition of peroxides used as cross-linking agents in the presentinvention can be brought about by applying thermal energy, shear,irradiation, reaction with other chemicals, or any combination of these.Both homolytically and heterolytically decomposed peroxide can be usedin the present invention. Non-limiting examples of suitable peroxidesinclude: diacetyl peroxide; di-tert-butyl peroxide; dibenzoyl peroxide;dicumyl peroxide; 2,5-dimethyl-2,5-di(benzoylperoxy)hexane;1,4-bis-(t-butylperoxyisopropyl)benzene; t-butylperoxybenzoate;2,5-dimethyl-2,5-di-(t-butylperoxy)hexyne-3, such as Trigonox 145-45B,marketed by Akrochem Corp. of Akron, Ohio; 1,1-bis(t-butylperoxy)-3,3,5tri-methylcyclohexane, such as Varox 231-XL, marketed by R.T. VanderbiltCo., Inc. of Norwalk, Conn.; and di-(2,4-dichlorobenzoyl)peroxide. Thecross-linking agents can be blended in total amounts of about 0.05 partsto about 5 parts, more preferably about 0.2 part to about 3 parts, andmost preferably about 0.2 part to about 2 parts, by weight of thecross-linking agents per 100 parts by weight of the unsaturated polymer.

Each cross-linking agent has a characteristic decomposition temperatureat which 50% of the cross-linking agent has decomposed when subjected tothat temperature for a specified time period (t_(1/2)). For example,1,1-bis-(t-butylperoxy)-3,3,5-tri-methylcyclohexane at t_(1/2)=0.1 hrhas a decomposition temperature of 138° C. and2,5-dimethyl-2,5-di-(t-butylperoxy)hexyne-3 at t_(1/2)=0.1 hr has adecomposition temperature of 182° C. Two or more cross-linking agentshaving different characteristic decomposition temperatures at the samet_(1/2) may be blended in the composition. For example, where at leastone cross-linking agent has a first characteristic decompositiontemperature less than 150° C., and at least one cross-linking agent hasa second characteristic decomposition temperature greater than 150° C.,the composition weight ratio of the at least one cross-linking agenthaving the first characteristic decomposition temperature to the atleast one cross-linking agent having the second characteristicdecomposition temperature can range from 5:95 to 95:5, or morepreferably from 10:90 to 50:50.

Besides the use of chemical cross-linking agents, exposure of thecomposition to radiation also can serve as a cross-linking agent.Radiation can be applied to the unsaturated polymer mixture by any knownmethod, including using microwave or gamma radiation, or an electronbeam device. Additives may also be used to improve radiation curing ofthe diene polymer.

The rubber and cross-linking agent may be blended with aco-cross-linking agent, which may be a metal salt of an unsaturatedcarboxylic acid. Examples of these include zinc and magnesium salts ofunsaturated fatty acids having 3 to 8 carbon atoms, such as acrylicacid, methacrylic acid, maleic acid, and fumaric acid, palmitic acidwith the zinc salts of acrylic and methacrylic acid being mostpreferred. The unsaturated carboxylic acid metal salt can be blended ina rubber either as a preformed metal salt, or by introducing anα,β-unsaturated carboxylic acid and a metal oxide or hydroxide into therubber composition, and allowing them to react in the rubber compositionto form a metal salt. The unsaturated carboxylic acid metal salt can beblended in any desired amount, but preferably in amounts of about 10parts to about 60 parts by weight of the unsaturated carboxylic acid per100 parts by weight of the synthetic rubber.

The core compositions used in the present invention may also incorporateone or more of the so-called “peptizers”. The peptizer preferablycomprises an organic sulfur compound and/or its metal or non-metal salt.Examples of such organic sulfur compounds include thiophenols, such aspentachlorothiophenol, 4-butyl-o-thiocresol, 4 t-butyl-p-thiocresol, and2-benzamidothiophenol; thiocarboxylic acids, such as thiobenzoic acid;4,4′dithio dimorpholine; and, sulfides, such as dixylyl disulfide,dibenzoyl disulfide; dibenzothiazyl disulfide; di(pentachlorophenyl)disulfide; dibenzamido diphenyldisulfide (DBDD), and alkylated phenolsulfides, such as VULTAC marketed by Atofina Chemicals, Inc. ofPhiladelphia, Pa. Preferred organic sulfur compounds includepentachlorothiophenol, and dibenzamido diphenyldisulfide.

Examples of the metal salt of an organic sulfur compound include sodium,potassium, lithium, magnesium calcium, barium, cesium and zinc salts ofthe above-mentioned thiophenols and thiocarboxylic acids, with the zincsalt of pentachlorothiophenol being most preferred.

Examples of the non-metal salt of an organic sulfur compound includeammonium salts of the above-mentioned thiophenols and thiocarboxylicacids wherein the ammonium cation has the general formula [NR¹R²R³R⁴]⁺where R¹, R², R³ and R⁴ are selected from the group consisting ofhydrogen, a C₁-C₂₀ aliphatic, cycloaliphatic or aromatic moiety, and anyand all combinations thereof, with the most preferred being the NH₄⁺-salt of pentachlorothiophenol.

Additional peptizers include aromatic or conjugated peptizers comprisingone or more heteroatoms, such as nitrogen, oxygen and/or sulfur. Moretypically, such peptizers are heteroaryl or heterocyclic compoundshaving at least one heteroatom, and potentially plural heteroatoms,where the plural heteroatoms may be the same or different. Suchpeptizers include peptizers such as an indole peptizer, a quinolinepeptizer, an isoquinoline peptizer, a pyridine peptizer, purinepeptizer, a pyrimidine peptizer, a diazine peptizer, a pyrazinepeptizer, a triazine peptizer, a carbazole peptizer, or combinations ofsuch peptizers.

Suitable peptizers also may include one or more additional functionalgroups, such as halogens, particularly chlorine; a sulfur-containingmoiety exemplified by thiols, where the functional group is sulfhydryl(—SH), thioethers, where the functional group is —SR, disulfides,(R₁S—SR₂), etc.; and combinations of functional groups. Such peptizersare more fully disclosed in copending U.S. Application No. 60/752,475filed on Dec. 20, 2005 in the name of Hyun Kim et al, the entirecontents of which are herein incorporated by reference. A most preferredexample is 2,3,5,6-tetrachloro-4-pyridinethiol (TCPT).

The peptizer, if employed in the golf balls of the present invention, ispresent in an amount up to about 10, from about 0.01 to about 10,preferably of from about 0.10 to about 7, more preferably of from about0.15 to about 5 parts by weight per 100 parts by weight of the syntheticrubber component.

The core compositions can also comprise one or more accelerators of oneor more classes. Accelerators are added to an unsaturated polymer toincrease the vulcanization rate and/or decrease the vulcanizationtemperature. Accelerators can be of any class known for rubberprocessing including mercapto-, sulfenamide-, thiuram, dithiocarbamate,dithiocarbamyl-sulfenamide, xanthate, guanidine, amine, thiourea, anddithiophosphate accelerators. Specific commercial accelerators include2-mercaptobenzothiazole and its metal or non-metal salts, such asVulkacit Mercapto C, Mercapto MGC, Mercapto ZM-5, and ZM marketed byBayer AG of Leverkusen, Germany, Nocceler M, Nocceler MZ, and NoccelerM-60 marketed by Ouchisinko Chemical Industrial Company, Ltd. of Tokyo,Japan, and MBT and ZMBT marketed by Akrochem Corporation of Akron, Ohio.A more complete list of commercially available accelerators is given inThe Vanderbilt Rubber Handbook: 13^(th) Edition (1990, R.T. VanderbiltCo.), pp. 296-330, in Encyclopedia of Polymer Science and Technology,Vol. 12 (1970, John Wiley & Sons), pp. 258-259, and in Rubber TechnologyHandbook (1980, Hanser/Gardner Publications), pp. 234-236. Preferredaccelerators include 2-mercaptobenzothiazole (MBT) and its salts. Thesynthetic rubber composition can further incorporate from about 0.1 partto about 10 parts by weight of the accelerator per 100 parts by weightof the rubber. More preferably, the ball composition can furtherincorporate from about 0.2 part to about 5 parts, and most preferablyfrom about 0.5 part to about 1.5 parts, by weight of the accelerator per100 parts by weight of the rubber.

Fillers

The various polymeric compositions used to prepare the golf balls of thepresent invention also can incorporate one or more fillers. Such fillersare typically in a finely divided form, for example, in a size generallyless than about 20 mesh, preferably less than about 100 mesh U.S.standard size, except for fibers and flock, which are generallyelongated. Filler particle size will depend upon desired effect, cost,ease of addition, and dusting considerations. The appropriate amounts offiller required will vary depending on the application but typically canbe readily determined without undue experimentation.

The filler preferably is selected from the group consisting ofprecipitated hydrated silica, limestone, clay, talc, asbestos, barytes,glass fibers, aramid fibers, mica, calcium metasilicate, barium sulfate,zinc sulfide, lithopone, silicates, silicon carbide, diatomaceous earth,carbonates such as calcium or magnesium or barium carbonate, sulfatessuch as calcium or magnesium or barium sulfate, metals, includingtungsten, steel, copper, cobalt or iron, metal alloys, tungsten carbide,metal oxides, metal stearates, and other particulate carbonaceousmaterials, and any and all combinations thereof. Preferred examples offillers include metal oxides, such as zinc oxide and magnesium oxide. Inanother preferred aspect the filler comprises a continuous ornon-continuous fiber. In another preferred aspect the filler comprisesone or more so called nanofillers, as described in U.S. Pat. No.6,794,447 and copending U.S. patent application Ser. No. 10/670,090filed on Sep. 24, 2003 and copending U.S. patent application Ser. No.10/926,509 filed on Aug. 25, 2004, the entire contents of each of whichare incorporated herein by reference.

Inorganic nanofiller material generally is made of clay, such ashydrotalcite, phyllosilicate, saponite, hectorite, beidellite,stevensite, vermiculite, halloysite, mica, montmorillonite,micafluoride, or octosilicate. To facilitate incorporation of thenanofiller material into a polymer material, either in preparingnanocomposite materials or in preparing polymer-based golf ballcompositions, the clay particles generally are coated or treated by asuitable compatibilizing agent. The compatibilizing agent allows forsuperior linkage between the inorganic and organic material, and it alsocan account for the hydrophilic nature of the inorganic nanofillermaterial and the possibly hydrophobic nature of the polymer.Compatibilizing agents may exhibit a variety of different structuresdepending upon the nature of both the inorganic nanofiller material andthe target matrix polymer. Non-limiting examples include hydroxy-,thiol-, amino-, epoxy-, carboxylic acid-, ester-, amide-, andsiloxy-group containing compounds, oligomers or polymers. The nanofillermaterials can be incorporated into the polymer either by dispersion intothe particular monomer or oligomer prior to polymerization, or by meltcompounding of the particles into the matrix polymer. Examples ofcommercial nanofillers are various Cloisite grades including 10A, 15A,20A, 25A, 30B, and NA+ of Southern Clay Products (Gonzales, Tex.) andthe Nanomer grades including 1.24TL and C.30EVA of Nanocor, Inc.(Arlington Heights, Ill.).

Nanofillers when added into a matrix polymer, such as the polyalkenamerrubber, can be mixed in three ways. In one type of mixing there isdispersion of the aggregate structures within the matrix polymer, but onmixing no interaction of the matrix polymer with the aggregate plateletstructure occurs, and thus the stacked platelet structure is essentiallymaintained. As used herein, this type of mixing is defined as“undispersed”.

However, if the nanofiller material is selected correctly, the matrixpolymer chains can penetrate into the aggregates and separate theplatelets, and thus when viewed by transmission electron microscopy orx-ray diffraction, the aggregates of platelets are expanded. At thispoint the nanofiller is said to be substantially evenly dispersed withinand reacted into the structure of the matrix polymer. This level ofexpansion can occur to differing degrees. If small amounts of the matrixpolymer are layered between the individual platelets then, as usedherein, this type of mixing is known as “intercalation”.

In some circumstances, further penetration of the matrix polymer chainsinto the aggregate structure separates the platelets, and leads to acomplete disruption of the platelet's stacked structure in theaggregate. Thus, when viewed by transmission electron microscopy (TEM),the individual platelets are thoroughly mixed throughout the matrixpolymer. As used herein, this type of mixing is known as “exfoliated”.An exfoliated nanofiller has the platelets fully dispersed throughoutthe polymer matrix; the platelets may be dispersed unevenly butpreferably are dispersed evenly.

While not wishing to be limited to any theory, one possible explanationof the differing degrees of dispersion of such nanofillers within thematrix polymer structure is the effect of the compatibilizer surfacecoating on the interaction between the nanofiller platelet structure andthe matrix polymer. By careful selection of the nanofiller it ispossible to vary the penetration of the matrix polymer into the plateletstructure of the nanofiller on mixing. Thus, the degree of interactionand intrusion of the polymer matrix into the nanofiller controls theseparation and dispersion of the individual platelets of the nanofillerwithin the polymer matrix. This interaction of the polymer matrix andthe platelet structure of the nanofiller is defined herein as thenanofiller “reacting into the structure of the polymer” and thesubsequent dispersion of the platelets within the polymer matrix isdefined herein as the nanofiller “being substantially evenly dispersed”within the structure of the polymer matrix.

If no compatibilizer is present on the surface of a filler such as aclay, or if the coating of the clay is attempted after its addition tothe polymer matrix, then the penetration of the matrix polymer into thenanofiller is much less efficient, very little separation and nodispersion of the individual clay platelets occurs within the matrixpolymer.

Physical properties of the polymer will change with the addition ofnanofiller. The physical properties of the polymer are expected toimprove even more as the nanofiller is dispersed into the polymer matrixto form a nanocomposite.

Materials incorporating nanofiller materials can provide these propertyimprovements at much lower densities than those incorporatingconventional fillers. For example, a nylon-6 nanocomposite materialmanufactured by RTP Corporation of Wichita, Kans., uses a 3% to 5% clayloading and has a tensile strength of 11,800 psi and a specific gravityof 1.14, while a conventional 30% mineral-filled material has a tensilestrength of 8,000 psi and a specific gravity of 1.36. Usingnanocomposite materials with lower inorganic materials loadings thanconventional fillers provides the same properties, and this allowsproducts comprising nanocomposite fillers to be lighter than those withconventional fillers, while maintaining those same properties.

Nanocomposite materials are materials incorporating up to about 20%, orfrom about 0.1% to about 20%, preferably from about 0.1% to about 15%,and most preferably from about 0.1% to about 10% of nanofiller reactedinto and substantially dispersed through intercalation or exfoliationinto the structure of an organic material, such as a polymer, to providestrength, temperature resistance, and other property improvements to theresulting composite. Descriptions of particular nanocomposite materialsand their manufacture can be found in U.S. Pat. No. 5,962,553 toEllsworth, U.S. Pat. No. 5,385,776 to Maxfield et al., and U.S. Pat. No.4,894,411 to Okada et al. Examples of nanocomposite materials currentlymarketed include M1030D, manufactured by Unitika Limited, of Osaka,Japan, and 1015C2, manufactured by UBE America of New York, N.Y.

When nanocomposites are blended with other polymer systems, thenanocomposite may be considered a type of nanofiller concentrate.However, a nanofiller concentrate may be more generally a polymer intowhich nanofiller is mixed; a nanofiller concentrate does not requirethat the nanofiller has reacted and/or dispersed evenly into the carrierpolymer.

The nanofiller material is added in an amount up to about 20 wt %, fromabout 0.1% to about 20%, preferably from about 0.1% to about 15%, andmost preferably from about 0.1% to about 10% by weight (based on thefinal weight of the polymer matrix material) of nanofiller reacted intoand substantially dispersed through intercalation or exfoliation intothe structure of the polymer matrix.

If desired, the various polymer compositions used to prepare the golfballs of the present invention can additionally contain otherconventional additives such as plasticizers, pigments, antioxidants,U.V. absorbers, optical brighteners, or any other additives generallyemployed in plastics formulation or the preparation of golf balls.

Another particularly well-suited additive for use in the various polymercompositions used to prepare the golf balls of the present inventionincludes compounds having the general formula:

(R₂N)_(m)—R′—(X(O)_(n)OR_(y))_(m),

where R is hydrogen, or a C₁-C₂₀ aliphatic, cycloaliphatic or aromaticsystems; R′ is a bridging group comprising one or more C₁-C₂₀ straightchain or branched aliphatic or alicyclic groups, or substituted straightchain or branched aliphatic or alicyclic groups, or aromatic group, oran oligomer of up to 12 repeating units including, but not limited to,polypeptides derived from an amino acid sequence of up to 12 aminoacids; and X is C or S or P with the proviso that when X═C, n=1 and y=1and when X═S, n=2 and y=1, and when X═P, n=2 and y=2. Also, m=1-3. Thesematerials are more fully described in copending U.S. patent applicationSer. No. 11/182,170, filed on Jul. 14, 2005, the entire contents ofwhich are incorporated herein by reference.

Preferably the material is selected from the group consisting of4,4′-methylene-bis-(cyclohexylamine)carbamate (commercially availablefrom R.T. Vanderbilt Co., Norwalk Conn. under the tradename Diak® 4),11-aminoundecanoicacid, 12-aminododecanoic acid, epsilon-caprolactam;omega-caprolactam, and any and all combinations thereof.

In an especially preferred aspect, a nanofiller additive component inthe golf ball of the present invention is surface modified with acompatibilizing agent comprising the earlier described compounds havingthe general formula:

(R₂N)_(m)—R′—(X(O)_(n)OR_(y))_(m),

A most preferred aspect would be a filler comprising a nanofiller claymaterial surface modified with an amino acid including12-aminododecanoic acid. Such fillers are available from Nanonocor Co.under the tradename Nanomer 1.24TL.

The filler can be blended in variable effective amounts, such as amountsof greater than 0 to at least about 80 parts, and more typically fromabout 10 parts to about 80 parts, by weight per 100 parts by weight ofthe base rubber. If desired, the rubber composition can additionallycontain effective amounts of a plasticizer, an antioxidant, and anyother additives generally used to make golf balls.

The modified ionomer composition used as a component of the golf ballsof the present invention may also be further modified by addition of amonomeric aliphatic and/or aromatic amide as described in copendingapplication Ser. No. 11/592,109 filed on Nov. 1, 2006 in the name ofHyun Kim et al., the entire contents of which are hereby incorporated byreference.

Golf balls within the scope of the present invention also can include,in suitable amounts, one or more additional ingredients generallyemployed in golf ball compositions. Agents provided to achieve specificfunctions, such as additives and stabilizers, can be present. Examplarysuitable ingredients include colorants, antioxidants, colorants,dispersants, mold releasing agents, processing aids, fillers, and anyand all combinations thereof. Although not required, UV stabilizers, orphoto stabilizers such as substituted hydroxphenyl benzotriazoles may beutilized in the present invention to enhance the UV stability of thefinal compositions. An example of a commercially available UV stabilizeris the stabilizer sold by Ciba Geigy Corporation under the tradenameTINUVIN.

The methods of making the presently described modified ionomercompositions used in the golf balls can incorporate a number of knownprocesses. The ionomer and CAS can be mixed together using dry blendingequipment, such as a tumbler mixer, V-blender, or ribbon blender, or byusing a mill, internal mixer, extruder or combinations of these, with orwithout application of thermal energy to produce melting or chemicalreaction. For example, the CAS can be premixed with the ionomer to forma concentrate having a high concentration of CAS. Then, this concentratecan be introduced into the base ionomer using dry blending or meltmixing. The CAS also can be added to a color concentrate, which is thenadded to the composition to impart a white color to golf ball. Anycombination of the above-mentioned mixing processes can be used.

Also described herein are methods for making golf ball covers andintermediate layers incorporating the above-described modified ionomercomposition.

The various formulations for the intermediate layer and/or cover layermay be produced using a twin-screw extruder or may be blended manuallyor mechanically prior to the addition to the injection molder feedhopper. Finished golf balls may be prepared by initially positioning thesolid, preformed core in an injection-molding cavity, followed byuniform injection of the intermediate layer and/or cover layercomposition sequentially over the core. The cover formulations can beinjection molded around the cores to produce golf balls of the requireddiameter.

Alternatively, the cover layers may also be formed around the core byfirst forming half shells by injection molding followed by compressionmolding the half shells about the core to form the final ball.

Covers may also be formed around the cores using compression molding.Cover materials for compression molding may also be extruded or blendedresins or castable resins such as polyurethane.

Typically the golf ball core is made by mixing together the unsaturatedpolymer, cross-linking agents, and other additives with or withoutmelting them. Dry blending equipment, such as a tumbler mixer, Vblender, ribbon blender, or two-roll mill, can be used to mix thecompositions. The golf ball compositions can also be mixed using a mill,internal mixer such as a Banbury or Farrel continuous mixer, extruder orcombinations of these, with or without application of thermal energy toproduce melting. The various core components can be mixed together withthe cross-linking agents, or each additive can be added in anappropriate sequence to the milled unsaturated polymer. In anothermethod of manufacture the cross-linking agents and other components canbe added to the unsaturated polymer as part of a concentrate using dryblending, roll milling, or melt mixing. If radiation is a cross-linkingagent, then the mixture comprising the unsaturated polymer and otheradditives can be irradiated following mixing, during forming into a partsuch as the core of a ball, or after forming.

The resulting mixture can be subjected to, for example, a compression orinjection molding process, to obtain solid spheres for the core. Thepolymer mixture is subjected to a molding cycle in which heat andpressure are applied while the mixture is confined within a mold. Thecavity shape depends on the portion of the golf ball being formed. Thecompression and heat liberates free radicals by decomposing one or moreperoxides, which initiate cross-linking. The temperature and duration ofthe molding cycle are selected based upon the type of peroxide andpeptizer selected. The molding cycle may have a single step of moldingthe mixture at a single temperature for fixed time duration.

For example, a preferred mode of preparation for the cores used in thepresent invention is to first mix the core ingredients on a two-rollmill, to form slugs of approximately 30-40 g, and then compression-moldin a single step at a temperature between 150 to 180° C., for a timeduration between 5 and 12 minutes.

The various core components may also be combined to form a golf ball byan injection molding process, which is also well known to one ofordinary skill in the art. The curing time depends on the variousmaterials selected, and those of ordinary skill in the art will bereadily able to adjust the curing time upward or downward based on theparticular materials used and the discussion herein.

The golf ball of the present invention may comprise from 0 to 5,preferably from 0 to 3, more preferably from 1 to 3, most preferably 1to 2 intermediate layer(s).

In one preferred aspect, at least one of the intermediate layerscomprises the novel blend compositions described herein.

In one preferred aspect, the golf ball is a three-piece ball with themodified ionomer composition of the present invention, used in theintermediate or mantle layer. In a more preferred aspect the three-pieceball has the modified ionomer composition of the present invention usedin the intermediate or mantle layer and a cover comprising athermoplastic elastomer, a thermoplastic or thermoset polyurethane, anionomer, or the reaction product of an ethylene/(meth)acrylic acidcopolymers and/or an ethylene/(meth)acrylic acid/alkyl(meth)acrylateterpolymers with a styrenic block copolymer and a metal hydroxide, metaloxide, metal stearate, metal carbonate, or metal acetate.

In another preferred aspect, the golf ball is a four-piece ball with themodified ionomer composition of the present invention, used in one ofthe two intermediate or mantle layers in the golf ball. In a morepreferred aspect the four-piece ball has the modified ionomercomposition of the present invention used in the inner mantle orintermediate layer. In an especially preferred aspect, the four-pieceball has the modified ionomer composition of the present invention, usedin the inner mantle or intermediate layer and a cover comprising athermoplastic elastomer such as a thermoplastic or thermosetpolyurethane, an ionomer, or the reaction product of anethylene/(meth)acrylic acid copolymers and/or an ethylene/(meth)acrylicacid/alkyl(meth)acrylate terpolymers with a styrenic block copolymer anda metal hydroxide, metal oxide, metal stearate, metal carbonate, ormetal acetate.

In another preferred aspect, the golf ball is a four-piece ball with themodified ionomer composition of the present invention used in one of thetwo intermediate or mantle layers in the golf ball. In a more preferredaspect the four-piece ball has the modified ionomer composition of thepresent invention, used in the outer mantle or outer intermediate layer.In an especially preferred aspect, the four-piece ball has the modifiedionomer composition of the present invention used in the outer mantle orouter intermediate layer and a cover comprising a thermoplasticelastomer such as a thermoplastic or thermoset polyurethane, an ionomer,or the reaction product of an ethylene/(meth)acrylic acid copolymersand/or an ethylene/(meth)acrylic acid/alkyl(meth)acrylate terpolymerswith a styrenic block copolymer and a metal hydroxide, metal oxide,metal stearate, metal carbonate, or metal acetate.

The chelating agent salt used in the modified ionomer composition of thepresent invention is present in an amount of from about 1 to about 25,preferably about 2 to about 20, more preferably from about 3 to about 15wt % (based on the total weight of modified ionomer composition).

The ionomer used in the modified ionomer composition of the presentinvention is present in an amount of from about 75 to about 99,preferably about 80 to about 98, more preferably from about 85 to about97 wt % (based on the total weight of modified ionomer composition).

The modified ionomer composition of the present invention has a materialShore D hardness of from about 25 to about 85, preferably from about 30to about 80, more preferably from about 35 to about 75.

The modified ionomer composition of the present invention has a flexuralmodulus from about 5 to about 500, preferably from about 15 to about400, more preferably from about 20 to about 300, still more preferablyfrom about 25 to about 200, and most preferably from about 30 to about150 kpsi.

Spheres of the modified ionomer composition of the present invention maybe made by injection molding for the purposes of evaluating theirproperty performance. The modified ionomer composition used in thepresent invention when formed into such spheres has a PGA compression offrom about 30 to about 200, preferably from about 35 to about 185, morepreferably from about 45 to about 180; and a COR greater than about0.500, preferably greater than 0.600, more preferably greater than about0.650, and most preferably greater than 0.700 at 125 ft/sec inboundvelocity.

The core of the balls may have a diameter of from about 0.5 to about1.62, preferably from about 0.7 to about 1.60, more preferably fromabout 1 to about 1.58, yet more preferably from about 1.20 to about1.54, and most preferably from about 1.40 to about 1.50 in.

The core of the balls also may have a PGA compression of less than about140, preferably less than about 120, more preferably less than about100, yet more preferably less than about 90, and most preferably lessthan about 80.

The various core layers (including the center) may each exhibit adifferent hardness. The difference between the center hardness and thatof the next adjacent layer, as well as the difference in hardnessbetween the various core layers may be greater than 2, preferablygreater than 5, most preferably greater than 10 units of Shore D.

In one preferred aspect, the hardness of the center and each sequentiallayer increases progressively outwards from the center to outer corelayer.

In another preferred aspect, the hardness of the center and eachsequential layer decreases progressively inwards from the outer corelayer to the center.

The one or more intermediate layers of the golf balls may have athickness of about 0.01 to about 0.50 or about 0.01 to about 0.20,preferably from about 0.02 to about 0.30 or from about 0.02 to about0.15, more preferably from about 0.03 to about 0.20 or from about 0.03to about 0.10, and most preferably from about 0.03 to about 0.10 orabout 0.03 to about 0.06 in.

The one or more intermediate layers of the golf balls also may have ahardness as measured on the ball of greater than about 25, preferablygreater than about 30, more preferably greater than about 40, and mostpreferably greater than about 50, Shore D units.

The cover layer of the balls may have a thickness of about 0.01 to about0.10, preferably from about 0.02 to about 0.08, more preferably fromabout 0.03 to about 0.06 in.

The cover layer the balls may have a Shore D hardness as measured on theball from about 35 to about 70, preferably from about 45 to about 70 orabout 50 to about 70, more preferably from 47 to about 68 or about 45 toabout 70, and most preferably from about 50 to about 65.

The COR of the golf balls may be greater than about 0.760, preferablygreater than about 0.780, more preferably greater than 0.790, mostpreferably greater than 0.795, and especially greater than 0.800 at 125ft/sec inbound velocity.

EXAMPLES

Examples of the invention are given below by way of illustration and notby way of limitation.

The properties of C.O.R., Shore D hardness (measured on both thematerial and on the resulting spheres) were conducted using the testmethods as defined below.

Core or ball diameter was determined by using standard linear calipersor size gauge.

Compression is measured by applying a spring-loaded force to the golfball center, golf ball core, or the golf ball to be examined, with amanual instrument (an “Atti gauge”) manufactured by the Atti EngineeringCompany of Union City, N.J. This machine, equipped with a Federal DialGauge, Model D81-C, employs a calibrated spring under a known load. Thesphere to be tested is forced a distance of 0.2 inch (5 mm) against thisspring. If the spring, in turn, compresses 0.2 inch, the compression israted at 100; if the spring compresses 0.1 inch, the compression valueis rated as 0. Thus more compressible, softer materials will have lowerAtti gauge values than harder, less compressible materials. Compressionmeasured with this instrument is also referred to as PGA compression.The approximate relationship that exists between Atti or PGA compressionand Riehle compression can be expressed as:

(Atti or PGA compression)=(160-Riehle Compression).

Thus, a Riehle compression of 100 would be the same as an Atticompression of 60.

Initial velocity of a golf ball after impact with a golf club isgoverned by the United States Golf Association (“USGA”). The USGArequires that a regulation golf ball can have an initial velocity of nomore than 250 feet per second±2% or 255 feet per second. The USGAinitial velocity limit is related to the ultimate distance that a ballmay travel (280 yards±6%), and is also related to the coefficient ofrestitution (“COR”). The coefficient of restitution is the ratio of therelative velocity between two objects after direct impact to therelative velocity before impact. As a result, the COR can vary from 0 to1, with 1 being equivalent to a perfectly or completely elasticcollision and 0 being equivalent to a perfectly plastic or completelyinelastic collision. Since a ball's COR directly influences the ball'sinitial velocity after club collision and travel distance, golf ballmanufacturers are interested in this characteristic for designing andtesting golf balls.

One conventional technique for measuring COR uses a golf ball or golfball subassembly, air cannon, and a stationary steel plate. The steelplate provides an impact surface weighing about 100 pounds or about 45kilograms. A pair of ballistic light screens, which measure ballvelocity, are spaced apart and located between the air cannon and thesteel plate. The ball is fired from the air cannon toward the steelplate over a range of test velocities from 50 ft/s to 180 ft/sec (forthe tests used herein the velocity was 125 ft/sec). As the ball travelstoward the steel plate, it activates each light screen so that the timeat each light screen is measured. This provides an incoming time periodproportional to the ball's incoming velocity. The ball impacts the steelplate and rebounds though the light screens, which again measure thetime period required to transit between the light screens. This providesan outgoing transit time period proportional to the ball's outgoingvelocity. The coefficient of restitution can be calculated by the ratioof the outgoing transit time period to the incoming transit time period,COR=T_(Out)/T_(in).

A “Mooney” viscosity is a unit used to measure the plasticity of raw orunvulcanized rubber. The plasticity in a Mooney unit is equal to thetorque, measured on an arbitrary scale, on a disk in a vessel thatcontains rubber at a temperature of 100° C. and rotates at tworevolutions per minute. The measurement of Mooney viscosity is definedaccording to ASTM D-1646.

Shore D hardness was measured in accordance with ASTM Test D2240.

Melt flow index (12) was measured in accordance with ASTM D-1238,Condition 230° C/2.16 kg.

Example 1

A blend of an ionomer (comprising a zinc salt of the polymer of ethyleneand acrylic acid with a final acid content of 15 wt % and a Shore Dhardness of 60D) and the tetra sodium salt of ethylene diaminetetraacetic acid (sodium EDTA) was prepared by extrusion as summarizedin Table 1. Spheres having a diameter of 1.52 in were then prepared fromthe resulting resin by standard injection molding techniques. ForComparative Example 1 a sphere was made under identical conditions fromjust the ionomer material and no added sodium EDTA. Table 1 representsthe physical properties of samples of the modified ionomer compositionof the present invention.

TABLE 1 Sphere Physicals Tested on Ionomer Modified With Na Salt ofEDTA. Comp Ex 1 Ex 1 Ionomer 100 100 Na salt of EDTA (pph) 5 Spherephysicals MFI 11 18 Shore D 60.1 63.9 COR (125 ft/sec) 0.625 0.665

The data in Table 1 shows that addition of the sodium EDTA to theionomer results in an increase in proccessability as shown by theincrease in melt flow index (I2) and an increase in resiliency or speedas shown by increasing COR while maintaining or showing only a slightincrease in hardness as measured by Shore D.

Examples 2-4

A series of blends of an ionomer (comprising a zinc salt of the polymerof ethylene and acrylic acid with a final acid content of 15 wt % and aShore D hardness of 60D) and varying amounts of sodium poly(acrylicacid) were prepared by extrusion as summarized in Table 2. Sphereshaving a diameter of 1.52 in were then prepared from the resulting resinby standard injection molding techniques. For Comparative Example 2, asphere was made under identical conditions from just the ionomermaterial and no added sodium poly(acrylic acid). Table 2 represents thephysical properties of samples of the modified ionomer composition ofthe present invention.

TABLE 2 Sphere Physicals Tested on Ionomer Modified With Na Salt of PAA.Comp Example Example Example Ex 2 2 3 4 Ionomer^(a) 100 100 100 100 Nasalt of poly(acrylic 3 5 10 acid)^(b) Sphere physicals MFI 9.5 14.2 15.715 Shore D 62.2 61.2 63.3 65.2 COR (125 ft/sec) 0.677 0.691 0.711 0.731^(a)Zinc salt of a polymer of ethylene and acrylic acid with a finalacid content of 15 wt % and a Shore D hardness of 60D ^(b)The sodiumpoly(acrylic acid) is commercially available from Aldrich

The data in Table 2 shows that addition of the sodium salt ofpoly(acrylic acid) results in an increase in proccessability as shown bythe increase in melt flow index (I2) and an increase in resiliency orspeed as shown by increasing COR, while maintaining or showing only aslight increase in hardness as measured by Shore D.

1. A golf ball comprising; 1) a core comprising a center, 2) an outercover layer; and 3) one or more intermediate layers, wherein at leastone of the outer cover layer or intermediate layer comprises a blendcomposition of (A) of from about 75 to about 99 wt % (based on thecombined weight of Components A and B) of one or more ionomers; and (B)of from about 1 to about 25 wt % (based on the combined weight ofComponents A and B) of one or more chelating agent salts; and whereinsaid blend composition has a flexural modulus of from about 5 to about500 kpsi, and a Shore D hardness of from about 25 to about
 85. 2. Thegolf ball of claim 1 wherein in said blend composition; A) Component Ais present in an amount of from about 80 to about 98 wt % (based on thecombined weight of Components A and B) one or more ionomers; and B)Component B is present in an amount of from about 2 to about 20 wt %(based on the combined weight of Components A and B) and comprises oneor more metal or ammonium salts of an unsaturated poly(carboxylic acid)or one or more metal or ammonium salts of a polyamino carboxylic acid;and wherein said blend composition has a flexural modulus of from about15 to about 400 kpsi, and a Shore D hardness of from about 30 to about80.
 3. The golf ball of claim 1 wherein in said blend composition; A)Component A is present in an amount of from about 85 to about 97 wt %(based on the combined weight of Components A and B) one or moreionomers and B) Component B is present in an amount of from about 3 toabout 15 wt % (based on the combined weight of Components A and B) of asodium salt of an unsaturated poly(carboxylic acid) or a sodium salt ofa polyamino carboxylic acid; and wherein the blend composition has aflexural modulus of from about 200 to about 300 kpsi., and a Shore Dhardness of from about 35 to about
 75. 4. The golf ball of claim 1wherein; 1) at least one of the intermediate layers comprises a blendcomposition of; (A) of from about 75 to about 99 wt % (based on thecombined weight of Components A and B) of one or more ionomers; and (B)of from about 1 to about 25 wt % (based on the combined weight ofComponents A and B) of the disodium salt of ethylene diaminetetraaceticacid or the sodium salt of poly(meth)acrylic; and wherein said blendcomposition has a flexural modulus of from about 5 to about 500 kpsi,and a Shore D hardness of from about 25 to about 85; and 2) the outercover layer comprises a polymer selected from the group consisting ofthermoset polyurethanes, thermoset polyureas, thermoplasticpolyurethanes, thermoplastic polyureas, ionomers, styrenic blockcopolymers, ethylene/(meth)acrylic acid copolymers, orethylene/(meth)acrylic acid/alkyl(meth)acrylate terpolymers, a unimodalionomer, a bimodal ionomer, a modified unimodal ionomer, a modifiedbimodal ionomer and any and all combinations thereof.
 5. The golf ballof claim 2, wherein when Component B is an unsaturated poly(carboxylicacid), the unsaturated poly(carboxylic acid) is not produced from amono-olefin or α-olefin.
 6. The golf ball of claim 5, wherein the metalor ammonium salt of unsaturated poly(carboxylic acid) is selected from ametal or ammonium salt of poly(acrylic), poly(methacrylic),poly(ethacrylic), poly(α-chloroacrylic), poly(crotonic), poly(maleic),poly(fumaric), or poly(itaconic) acid.
 7. The golf ball of claim 2,wherein Component B is a polyamino carboxylic acid selected fromethylenediamine-N,N,N′,N′-tetraacetic acid (EDTA); disodium, trisodium,tetrasodium, dipotassium, tripotassium, dilithium and diammonium saltsof EDTA; 1,3-diamino-2-hydroxypropane-N,N,N′,N′-tetraacetic acid;1,3-diaminopropane-N,N,N′,N′-tetraacetic acid;O,O′-bis(2-aminoethyl)ethyleneglycol-N,N,N′,N′-tetraacetic acid; or7,19,30-trioxa-1,4,10,13,16,22,27,33-octaazabicyclo[11,11,11]pentatriacontanehexahydrobromide.
 8. The golf ball of claim 1, wherein the sodium saltof poly(meth)acrylic acid is a sodium salt of poly(acrylic acid).
 9. Thegolf ball of claim 4, wherein the sodium salt of poly(meth)acrylic acidis a sodium salt of poly(acrylic acid).